There were many trains over the years that carried the name Orient Express, operating over at least five different routes.

There is no longer a train by that name, other than the super-expensive nostalgia operations. That latter train has, at times, been hauled by preserved steam on special occasions.

By the 1990, the trains that carried the Orient express designation were already tired old trains -- with mostly second class coaches and only a few sleeping cars. I rode that train a few times in the 1980s and 1990s between Paris and Vienna. I can attest to the fact that it was not a luxury train.

As of 2005, there was still a Euro Night train (EN 262 / EN 263) with the name Orient Express. That train ran between Paris and Vienna, though not all coaches ran the entire route. The name has been officially retired for several years now. Again, at that time, this was just a regular night train, with no particular luxurious amenities, and my 2005 timetable does not even show a diner.

Yes, it is worth looking up Orient Express on Wikipedia for a much more detailed history.