They are the same manufacturer. Ixo and Premium X are in the PCT Group.
Also known as Premium & Collectibles Trading Co., Ltd. My Premium X Jeep Cherokee ran me $45 in 2013. The most recent Ixo I bought cost $40. So a little cheaper. My GUESS would be that, once the cost of tooling was amortized via Premium X, they could offer an Ixo a bit cheaper. I have not seen much to differ in quality between Ixo and Premium X, not even sure why they maintain both brands.BTW, the Jeep came out soon after the Neo version, which incorrectly had "wood" framing vertically between the doors. By the time they took my suggestion to correct it, the PX was out (and cheaper) so I got it.