What’s the difference between concat and uglify and minify?

Concatenation is just appending all of the static files into one large file.

Minification is just removing unnecesary whitespace and redundant / optional tokens like curlys and semicolons, and can be reversed by using a linter.

Uglification is the act of transforming the code into an “unreadable” form, that is, renaming variables/functions to hide the original intent… It is, also, irreversable.