ulimit & rlimit in Linux, are they the same thing?

Question

I see people use the terms ulimit & rlimit interchangeably, can I say they are referring to the same thing?

Solution

Referring to ulimit man page, it's a bash shell command to control the rlimits of the system and a part of bash-builtins like printf, read, source, etc.

Referring getrlimits page, it represents the APIs via C/C++ using system calls to control system rlimits. Additional glibc documentation on explains rlimits (= resource limits) better.