What is the difference between double-ampersand (&&) and semicolon (;) in Linux Bash?

Question

What is the difference between ampersand and semicolon in Linux Bash?

For example,

$ command1 && command2

vs

Answer 1

command1 && command2

command1 && command2 executes command2 if (and only if) command1 execution ends up successfully. In Unix jargon, that means exit code / return code equal to zero.

command1; command2

command1; command2 executes command2 after executing command1, sequentially. It does not matter whether the commands were successful or not.