stepmother vs. mother-in-law???

[94BANSHEE]

can these 2 EVER mean the same thing, or are they totally different?

i heard a wife call her husbands mother her stepmother. but i think she was wrong.

[mykwyner]

Your stepmother is your father's wife who is otherwise not related to you. Your father divorced or was widowed and got remarried. His new wife is your stepmother.

A mother-in-law is your spouse's mother.

Your mother-in-law can also be your spouse's stepmother.

Example: Mr. Smith's wife dies when his son, John, is 10 years old. Mr. Smith marries a new wife, Jane, two years later. Jane Smith becomes John's stepmother. Ten years later John marries you. Jane is then both a mother-in-law (to you) and a stepmother (to your husband, John).