What’s the difference between nikah mutaah and sigha mehramiyat?

We have only two types of marriage. One is temporary marriage and one is permanent marriage. In temporary marriage the duration of the marriage must be specified (like 1 year), and one the duration expires the marriage ends without a divorce.

Sigha Mahramiya is basically a marriage contract (usually temporary marriage contract) that’s done to make someone mahram to you. Nikkah usually refers to permanent marriage.