The statement that "One CD player has 24 bits, the other 18" makes no sense. Players do not "have" bits. The CDs have the bits, and they all have the same number--16 per sample, and 44,100 samples per second. No CD player in the world can give you more resolution than that (with an asterisk for HDCD).
These "specs" are concocted in marketing departments, and there is no meaningful way to compare the marketing inventions of one manufacturer to another--let alone any reason to. It's quite possible that "18 bits" and "24 bits" are not even referring to the same thing. (I suspect the latter may refer to 64x oversampling, but that's just a guess. And I doubt the "18-bit" machine is doing only 4x oversampling.)
Tell us what the two units are, and you will get some opinions.
These "specs" are concocted in marketing departments, and there is no meaningful way to compare the marketing inventions of one manufacturer to another--let alone any reason to. It's quite possible that "18 bits" and "24 bits" are not even referring to the same thing. (I suspect the latter may refer to 64x oversampling, but that's just a guess. And I doubt the "18-bit" machine is doing only 4x oversampling.)
Tell us what the two units are, and you will get some opinions.