2 + 3 = 5
is a mathematically true statement.
2 + 3 + 0 = 5
is mathematically true, and in fact is the same statement.
They've got different hash values though, because hash functions care about binary representations, not mathematical equivalence.

Good one
If you compare the signature on the bitcoin transaction (on an input of it actually, like a transaction is composed of multiple checks.) with a traditional
wet handwritten signature, then the malleability is like the signature being done in another color of ink. A grafologist would still conclude that the purported sender could have made that signature, if he didn't know that the real sender always used a very specific color and composition of ink.