I believe the "T" designates the ability to read CD-Text. Some CDs have Album/Artist name and track data encoded on them. A player needs to have the ability to decode that information in order to display it.
If you are thinking about purchasing this player, you may want to gather slightly more funds and purchase the cd 23. I had a 73T and it was good. The CD 23 is significantly better and can be had for as low as $700 here on Audiogon. Don't worry about the 'T' designation as it does nothing for improving the sound quality.
I heartily recommend the CD 23.