Hi scubamom,
That rules out some of the “other” possibilities so the two most likely causes are either the foundation you were having issues with affected your perception of how they compared or they are actually different.
2 ILD is less than most if not all people would be able to feel and is less than the normal ILD variation across the surface of a typical latex layer. The Old Beautiful (see the specs here) also had an inch less latex in the middle 24 ILD layer layer than the current Beautiful (see the specs here) which would have a firming effect.
Phoenix