What’s the difference between Apple Watch 6 and Apple Watch 6 SE?

There is no apple watch 6 SE,there is;

Apple watch 6 Gps only

Apple watch 6 Gps+cellular

Apple watch SE GPS only

Apple watch SE GPS+cellular

Apple watch 3 GPS only

These are all the watch available to buy from Apple.

The Apple Watch series 6 has an always-on display, which means that you can always see the time in the watch face. Also, it has blood oxygen monitoring, ECG and a 20% faster s6 chip. The Apple Watch SE, not 6 SE, has the same display as the series 6, but it isn’t always on. Also, it does not have ECG or Blood oxygen monitoring, and you can only buy it with an aluminium case in three colours and the nike edition, whereas the series 6 can be bought in 6 aluminium finishes, 3 stainless steel finishes and 2 titanium ones, and also from the Hermes and the nike collections.

https://www.apple.com/watch/compare/

The 6 GPS has blood oxygen app and a few other features that the SE doesn't have.

See here;

Apple Watch - Compare Models - Apple

We can all see the technical differences on the apple website but want to know more in reality, is it only the Oxygen level that makes any difference?