A week ago, during a rather challenging off-road ride on a very bumpy and hilly steep track, I swapped my bike for my "ebike mate's".
I have a Trek Powerfly 7 full suspension.
He has a Trek Powerfly 4 front suspension only.
Two models with the same frame, motor and battery, but with different accessories, mine being more expensive.
I, a novice, immediately noticed the lower quality on this demanding road. From the brakes, to the comfort, to the gear ratios, etc. He immediately said: "Wow! This is much better!".
I also noticed that my bike (the Powerfly 7) accelerates much faster downhill, as if the rolling coefficient were lower (he said it's because I'm... heavier than him

and my bike itself is heavier. I reminded him of Galileo's experiment on the Leaning Tower of Pisa... we argued hard for the next few kilometres as we are both quite nerdish astronomers

- we looked like The Big Bang Theory... ).
This doesn't mean that what you pay is what you get IN GENERAL, but I'm very happy that when I was about to buy the model 4, they offered me an upgrade for about $1000 with a big discount, and I took the deal.
Obviously I have fairly high requirements, given the type of routes I wanted to cover, the gradients and elevation gains, and the difficulty of finding parts here. So I had very few brands and models to locally shop from. But in short... the difference in quality is obvious, and my friend is thinking of upgrading now.