Similarities between Marshall’s and Robbins’ definitions : 

1. Both Marshall and Robbins in their respective definitions have treated economics as science. 

2. Both the economists have given priority to the humans first and then, resources. 

3. In Marshall’s theory, the central point is maximum welfare, whereas Robbins has mainly focused on economization. But the tendency of both the economists is one i.e. maximum satisfaction. 

4. In Marshall’s definition, the word ‘wealth’ is used, whereas in Robbins’ definition, limited resources has been used. To an extent, both these words are used in context to similar meaning because scarcity is a major characteristic of wealth. 

5. Prof. Robbins stated that limited resources need to be used very cautiously so that there could be maximum production for the interest of maximum people. Whereas, Prof. Marshall regarded it as maximum welfare.

Difference between the two definitions

• Difference in nature of definition : Marshall’s definition about economics is classificatory, whereas Robbins’ definition about economics is analytical. Marshall explained all the activities, either physical or non-materialist, economic or non-economic in normal life business as a subject of economics, whereas Robbins didn’t separate different activities, rather, he included the study of making choice in the subject matter of economic problem.
• Difference in contents : Marshall included in economics those monetary activities which are related to earning money and use of money whereas, Robbins studied about selection of human behaviour and regarded this process of selection to be an economic aspect or economic problem.
• Form of Economics : According to Prof. Marshall economics is a social science in which he mentions the economic activities of only those people who live in the society, whereas, according to Robbins’ definition, economics is a human science which studies selection behaviour of human beings.
• Differences in classification of resources : Marshall included only economic resources in the study of economics whereas Robbins included all such physical and non-material resources which are scarce.
• Nature of Economics : Marshall agrees that economics is positive science and normative science and he also classified economicsm in arts. Whereas Robbins mentioned economics as empirical Science. 
• Difference in Objective : Prof. Marshall explained that objective of economics is growth in welfare of human, whereas according to Robbins there are no such objectives in economics and also stated that there is no link between human welfare and economics.