Hi, They have nearly the same meaning. - 'A hobby' is an activity that you do for pleasure when you are not working. 'Reading, listening to music and watching movies are his favourite hobbies.' - 'An interest' is an activity or a subject that you enjoy and that you spend your free time doing or studying: 'My main interest was literature' 'Her main interests are music and tennis.'

Hello Idrees, A hobby* is an activity ( a leisure activity ) pursued in spare time for pleasure and relaxation. It is done in times when you are free to do things you enjoy. An interest* could be a hobby, it is in general something in which one is interested; whether a hobby or pursuit. It refers to a diversion that occupies one's time and thoughts, whereas a hobby could be enjoyable without necessarily exciting one's curiosity or concern. Pursuing any activity in free times such as listening to music or playing football is more of a hobby,since it is a source of happiness , entertainment and pleasure without deep thoughtful concern. It doesn't necessarily affect one or cause a deeper reflection on it. It is usually a regular practice. On the other hand, having an interest in a certain kind of music will involve more than just listening to it in spare time. It is then on one's mind and engages the person in other related activities such as reading, searching and inquiring about it.

Hi, both Cherry and Learner are correct.