Yes the B450 aorus m will work fine with both the 2600x and 2700.
2700 has 8 cores and 16 threads with a max 1 core turbo of 4.1ghz, although the max all core turbo is slighy lower.
2600x has 6 cores and 12 threads with a max 1 core turbo to 4.2ghz but again the max all core turbo is slightly lower.
Realistically in most games and work tasks the 2700x 8 cores will more then make up for the slightly higher turbo of the 2600x, so the 2700 has superior performance.
The 2700 has a much weaker cooler than the 2700x and theoretically turbos 200mhz lower than the 2700x, but the 2700 is still generally higher performqnce than a 2600x.
The 2600x is also great for gaming and productivity, but if you can streatch to a 2700, i would buy the 2700.