Suffixes: らしき versus っぽい


I came across the following sentence recently:

> バイトらしき女の子に優しく教えてくれた。

Strangely, it was my first time encountering this form of らしい and I understood
the meaning immediately, but it brought to mind two questions:

1) How does it differ, if at all, from the suffix っぽい? 2) Is it as archaic as
other -き form adjectives tend to be, or is it more commonly used due to the
fact that it can be added to essentially any appropriate noun?

Any insights would be greatly appreciated. Thanks.

