Technically, the TRD caps are not even listed as being able to fit either 1.8 or 2.4 engined Corolla. Honestly, the best thing to do is take a chance and try.
Also, the reason why the part numbers are different is because of where they are assembled. The tC was Japan and the XRS was either US or Canada. Hence, they have different suppliers for likely the same part. I've seen this with air filters, so there's probably a lot of parts like that with Toyota if a certain model is made on two continents.