They are the same thing, aren't they?
No, they aren't.
I think the first sentence of the Wikipedia page you referenced gives a nice, brief summary:
UTF-8 is a variable width character encoding capable of encoding all 1,112,064 valid code points in Unicode using one to four 8-bit bytes.
To elaborate:
Unicode is a standard, which defines a map from characters to numbers, the so-called code points, (like in the example below). For the full mapping, you can have a look here.
! -> U+0021 (21), " -> U+0022 (22), \# -> U+0023 (23)UTF-8 is one of the ways to encode these code points in a form a computer can understand, aka bits. In other words, it's a way/algorithm to convert each of those code points to a sequence of bits or convert a sequence of bits to the equivalent code points. Note that there are a lot of alternative encodings for Unicode.
Joel gives a really nice explanation and an overview of the history here.