You would call your husband's younger brother a brother-in-law.
You call your husband's senior brother simply a brother in-law. There is no difference whether he is a senior brother or a younger brother he remains your brother in-law.
In Malayalam, you call a younger brother "Chettan."
Your brother would call your husbands sister by her first name. Or, "my (sibling's) sister in law.
In Hindi, you would call your father's younger brother "chacha."
brother in law
Brother in-law
Sister-in-Law
The wife of your brother (younger or older than you) is your sister-in-law.
little brother
tamma
Uncle
You can call your elder brother as 'ANNA' and your younger brother as 'THAMBI'