Yes, the chambers are different.
This is my understanding of the CZ457 rifles; it may or may not be true/accurate.
When CZ introduced their 457 rifles, (pre-covid), their first MTR (Match Target Rifle) was the one in the walnut stock, (the 457 Varmint MTR). All of the actions of the 457 line-ups are the same, with either a "sporting" chamber, or the tighter "match" chamber designated with the MTR adder to the name. About a year later, CZ came out with their CZ457 Varmint Chassis. Again, it has the same action as all 457's but has the "sporting" chamber. I'm going to assume the price differential between the wooden stock MTR and the Varmint Chassis is due to the additional cost of the metal chassis and inflation. Around this same time CZ offered their chassis rifle with the MTR chamber, (the Varmint Precision Chassis MTR), with around a $100 adder over the Varmint Chassis for the "match" chamber.
From the CZ-USA website, I believe CZ only offers 3 rifles with the match chamber: the 457 Varmint MTR, 457 Varmint Precision Chassis MTR, and the 457 Varmint Precision Trainer MTR. Notice the MTR adder in their name?
I shoot ARA 50-yard bench rest factory class with my 457 Varmint MTR. I purchased that rifle because it had the match chamber, thinking I had to have a match chamber in order to compete. My experience has proven that to be wrong. There are plenty of people winning with short-barreled sporting chambers CZ's to prove my original thinking to be wrong. Did they win the barrel lottery? Perhaps, but I think the real reason is that these shooters have spent enough time shooting various lots of ammo with their rifles to understand how their rifles perform, and they have good shooting techniques.
In my case, the biggest enhancement I made in improving my gun's accuracy is when I purchased and began using wind flags.