'last year' vs 'in the last year'
Is there any difference between 'last year' and 'in the last year'?

Question

Answer

" Last year" is a specific past time which means a year before this year.
" In the last year" isn't a specific time which means at some point between last year until now. " In the last year" is used in The Present Perfect tense.
Example:

Simple Past:          I went to Hawaii last year.
Present Perfect:    I have been to Hawaii in the last year.

Answer

Last year I ate twenty pounds of chocolate. This could mean anytime last year. 
In the last year, I ate twenty pounds of chocolate between May and June.
Or they can be used in the same way.