ALMOST true.
Electrically, yes a 681EE and 681EEE are very close. Any differences border on negligible. However, the 681EE body and stylus are slightly physically different from the EEE. The EE cart body and has the mounting ears at a different angle, with a complimentary angle change to the stylus to get a 15 degree VTA as designed vis-a-vis the EEE.
A stylus for a EE can fit in a EEE body and will work, (and vice-versa) but getting the VTA and SRA right will be tricky. They aren't plug and play compatible without making a few critical adjustments to get the performance expected.