Is 100 mils the same as 100 milliliters?

Answer 1

It could be. "Mils" is a slang or shorthand term used by different people at different
times in different places to mean different things. It normally means "thousandths",
of something that is very clear and well understood by the people who say it to
each other.

Just in my own work and hobby experience, "mils" at different times and in different
activities has meant thousandths of a liter, a meter, an inch, an Ampere, and a volt.

Answer 2

No, 100 mils is not the same as 100 milliliters. Mils is a unit of length, equal to one-thousandth of an inch, while milliliters is a unit of volume used to measure liquids.