This still doesn't tell me how they differ. What are the factual objective measurable differences between E/L/T/P?

I was assigned an E14 once. Compared to a T14:

The case is all thick ABS.

It weighs like 2.4 kg, and the weight is unbalanced.

The USB-C charge only works at 20V, nothing less.

While charging it overheats and spins up the fans.

It came with a TN screen with terrible viewing angles, that could not be used in a brightly lit room. I didn't use the laptop for two months while I waited for a replacement screen from aliexpress.

Keyboard is much thinner, the trackpoint drifts easily.

Camera quality is worse, somehow it cannot handle sun-lit scenes. Microphone and speakers are similar to the T14.

It stopped receiving firmware updates after two years.

It uses about 0.5 W while suspended, so its tiny 48 Wh battery typically doesn't last the weekend with the lid closed.

The motherboard has design issues, a missing protection diode in the headphone jack microphone input ended up frying the CPU due to a ground loop. Meanwhile the T14 has eaten the same ground loop and even a 48V passive PoE in an accident and dealt with it by rebooting. A T450 from 2015 is still running.

Spoiler: they are all identical hardware, but marketed differently.