Essential difference between on and bind?

Essential difference between on and bind?

What is really the difference between .on() and .bind()? (excepting the version difference)
I've been using 1.64 version for a long time, and now I'm actually getting scolded for using the old .bind() method,
but I can barely understand the reasons for upgrading though.
I also wonder what methods do you guys use for the community plugins, and should we generally consider the back compatibility? The latest versions add quite a bit in weight, so maybe not all of the users want to upgrade...