You can start your answer by telling how LinkedIn and Instagram both are the finest examples of networking tools but how brands trust one platform more than the others. While Instagram with 1.386 billion users has taken away the brand promotion strategy quite efficiently, LinkedIn, with 8 crore active users, still lags in this aspect which is why the interviewer wants to know your opinion on whether or not they both can be used in a same way and if yes, they want to see you trying to bridge that gap. However, the knowledge of algorithms, regular posting of engaging and valuable content, forming and developing groups, and building your niche and brand over time can help businesses promote themselves, just like Instagram. Apart from utilizing LinkedIn to promote business organically, you can always run an effective ad campaign (although it requires a LinkedIn page) there or boost your post to get more views and engagement. These are some features you get on Instagram too and you have to be sharp enough first to observe and then express these methods of promoting business through Instagram and LinkedIn in front of your interviewer.