One is USB to TTL, also called serial port.

The other is USB to 232.

The difference between them is that the logic 1 (high level) voltage of RS232 signal is-15v, and the logic 0 (low level) voltage is+15v.

The voltage of TTL is 0v-5v, so the two interfaces are incompatible, and a level conversion chip like max232 is needed.

Generally, single chip microcomputer uses TTL serial port.

Industrial computer using 9-pin serial port is RS232 signal.

The simplest way to distinguish USB from 9-pin serial port is RS232 signal.