The first case creates a (non const) char array that is big enough to hold the string and initializes it with the contents of the string. The second case creates a char pointer and initializes it to point at the string literal, which is probably stored in read only memory.
Since strtok wants to modify the memory pointed at by the argument you pass it, the latter case causes undefined behavior (you're passing in a pointer that points at a (const) string literal), so its unsuprising that it crashes
