Difference Between Clustering and Classification (With Table)

In today’s world, machine learning is very important as artificial intelligence is seen as an integral part of it. The study of computer algorithms by using data is what machine learning does. They collect data, also known as ‘training data to predict and how it will perform the tasks. Machine learning is used in a variety of areas such as in medicine, filtering of emails etc. Clustering and Classification use statistical method for collecting data, especially in the field of machine learning.

Clustering vs Classification

The difference between Clustering and Classification is that Clustering organises the objects or data in clusters which may have similarities with each other, but the objects of two different cluster will be different from one another. The motive of clustering is to divide the whole data into different clusters. Whereas classification is a process where the objects are organised according to classes and rules are already predetermined. 

Clustering is also called cluster analysis in machine learning. It is the process in which there is a grouping of an object in such a way that the objects inside the clusters have similar properties, but when compared to another cluster, it is very much dissimilar to it. This technique of clustering is used in statistical and explorative data analysis in the process such as image analysis, data compression, information retrieval, pattern recognition, bioinformatics, computer graphics and machine learning.

Classification is also called statistical classification in machine learning. It is a process in which the objects are classified and put into a set of categorised compartments. Classification is done on the quantifiable observations. An algorithm that incorporates the classification is known as a classifier. Classification is based on a two-step process: learning step and classification step.

Comparison Table Between Clustering and Classification

Parameters of ComparisonClusteringClassification
DefinitionClustering is a technique in which objects in a group are clustered having similarities. Classification is a process in which observation is classified given as input by a computer program.
DataClustering does not require training data.Classification requires training data.
PhaseIt includes single-stage, i.e., grouping.It includes two-step: training data and testing.
LabellingIt deals with unlabelled data.It deals with both labeled and unlabelled data in its processes.
ObjectiveIts main objective is to unravel the hidden pattern as well as narrow relationships.Its objective is to define the group to which objects belong to.

What is Clustering?

Clustering is part of machine learning that groups the data into clusters with high similarity, but different clusters may differ. It is the method of unsupervised learning and is very commonly used for statistical data analysis. There are different types of clustering algorithms like K-means, DBSCAN, Fuzzy C-means, Hierarchical clustering, and Gaussian (EM).

Clustering does not require training data. In comparison to classification, clustering is less complex as it includes only the grouping of data. It does not give labels to every group like classification. It has a single step process known as Grouping. Clustering can be formulated as a multi-objective optimization problem that focuses on more than one problem.

Clustering was first created by Driver and Kroeber in the field of anthropology in the year 1932. Then it was introduced to the various field by various persons. Popularly clustering was used by Cartell for trait theory classification in personality psychology in 1943. It can be roughly distinguished as Hard Clustering and Soft Clustering. It has different applications such as customer segregation, social network analysis, detecting dynamic data trends, and cloud computing environments.

What is Classification?

Classification is basically used for pattern recognition where output value is given to the input value, just like clustering. Classification is a technique used in data mining but also used in machine learning. In Machine Learning, output plays an important role and there comes the need for Classification and Regression. Both are supervised learning algorithms, unlike clustering.

When output has a discreet value, then it is considered as a classification problem. Classification algorithms help predict the output of a given data when input is provided to them. There can be various types of classifications like binary classification, multi-class classification etc. Different types of classification also include Neural Networks, Linear Classifiers: Logistic Regression, Naïve Bayes Classifier: Random Forest, Decision Trees, Nearest Neighbor, Boosted Trees.

Various Applications Of Classification Algorithm includes Speech recognition, Biometric identification, Handwriting recognition, Email Spam Detection, Bank Loan Approval, Document classification etc. Classification requires training data, and it requires predefined data, unlike clustering. It is a very complex process. It is a result of supervised learning. It deals with both labelled and unlabeled data. It involves two processes: training and testing.

Main Differences Between Clustering and Classification

  1. Clustering is a technique in which objects in a group are clustered having similarities. It is a result of supervised learning. Classification is a process in which observation is classified given as input by a computer program. It is a result of unsupervised learning.
  2. Clustering does not require training data. Classification requires training data.
  3. Clustering includes single-stage, i.e. grouping. The classification includes two-step: training and testing.
  4. Clustering deals with unlabelled data. Classification deals with both labelled and unlabelled data in its processes.
  5. Clustering main objective is to unravel the hidden pattern as well as narrow relationships. The classification objective is to define the group to which objects belong to.


Clustering and Classification both are the statistical data analysis used in the field of machine learning. Both are important in managing algorithms. Both have the same function as dividing data into sets, one into clusters and the other into categories. Both are very important in the age of the digital world and artificial intelligence. 

Both are required for immense coupling of data and development.

Clustering and Classification also help to solve global issues like poverty, crime, diseases through the process of collecting data. Clustering has no exact definition to be defined properly and is very difficult to evaluate. Whereas Classification ‘classifier’ and is evaluated through common metrics.


  1. https://books.google.com/books?hl=en&lr=&id=HbfsCgAAQBAJ&oi=fnd&pg=PR7&dq=clustering+and+classification+&ots=RVS-xBcH89&sig=6vliHhJ_PgtjPExTofGjDlvacaM
  2. https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470027318.a5204.pub2
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