Like, Alike and Unlike

Like, Alike and Unlike.

Like and Alike Both are adjectives to similar. Predicative adjective. Adjective.

Like and Unlike Are prepositions. 

Alike.

Is a predicative adjective. Appear after a linking verb such as be. Example: Raissa and Larissa are alike. In this example, alike describe Raissa and Larissa. 

Like

As an adjective. It Is used immediately before a noun. Example: Raissa and Larissa work like teachers. The adjective "like" describes Raissa and Larissa's jobs in the example.      

As a preposition. Must be followed by objects. It can be used at the end or the beginning of the sentence. Examples: Raissa is like Larissa. Like Raissa, Larissa is tall. In both examples, the preposition like means that Raissa and Larissa are similar. 

Unlike

It is a preposition. It must be followed by objects. It can be used at the end or the beginning of the sentence. Examples: Raissa is unlike me. Unlike me, Raissa is tall. In both examples, the preposition, unlike means that I and Raissa are different.