Difference between Turing machine and Universal Turing machine
A universal Turing machine is just a Turing machine whose programming simulates other Turing machines.  That is, the input to the UTM is a description of a Turing machine&nbsp;$T$ and an input for&nbsp;$T$, and the UTM simulates&nbsp;$T$ on that input.

It's universal in the sense that, for any problem that can be solved by Turing machines, you could either use a Turing machine that directly solves that problem, or you could use a UTM and give it the description of a TM that directly solves the problem.

If you like, a UTM is an interpreter for (all) Turing machines.