The TRBX204 is the active version of the TRBX174 (which is a great bass) with 2 band EQ and PJ pickups and a bit more of a thicker neck. The 304 has double humbuckers and an EQ with a 5 way selector switch (which im not a fan of) and has more of a modern tone like a stingray.
Which you pick will mostly depend on personal preference. Personally, i’d rather have the 204 or go up to at least the TRBX504 which has better pickups, better EQ and passive/active switch vs the 304.
Here’s a review on them https://youtu.be/9LnhtzLZvis