Your first RE says, "find me a space that's at the beginning of the line, or find me a space at the end of a line." However, many programs that use REs, might read that as "find me a start of line, followed by a space or a space (and yes, that would be redundant and unnecessary), then an end of line."

Your second RE says, "find me either a beginning of line or an end of line".

It depends on what you actually want to get as to how you would change that to work for you.

Both ^ and $ are special characters and should be escaped if you're actually looking for them.