'Alike' is used as an adjective: They look alike. 'Like' is used as a preposition: He's looks like his brother.

'Like' is a preposition and it means 'similar to'. E.g.: My mobile is like yours. 'Alike' is an adverb. It means 'in a similar way' E.g.: Carla and Anne usually think alike.

You cant use them in the same way without adjustments. They look alike They look like each other In my opinion alike is used if the things compared do not look exactly the same. While look like each other implies that they look very similar.