1, with different meanings: the mid-term usually refers to the mid-term exam, which is a term in the field of education; Mid-$ TERM, on the other hand, means mid-term and can be used to describe the intermediate stage of a period of time or plan.
2. Different usage: Mid-term is usually used as the subject or predicative in a sentence, such as "Mid-term exam is next week" (Mid-term exam will be held next week). Mid-$ TERM is usually used as an adjective to modify nouns, such as "the medium-term plan includes a series of important projects"