Summary:

Different amounts of sand and gravel are generated on android and windows 10.

It seems that less gravel is generated on android than in Windows 10. And in any case, the generation of sand and gravel is different.

The generation of sand and gravel is different near lakes and rivers. This works in any world, but I'll provide an example:

(1.17.30)

Seed: -1711352119
Coords: -2500 77 -892

(1.17.40)

Seed: 47664
Coords: 9546 59 1846

Android

Windows 10

Steps to reproduce:

1. Create a new world on Android and Windows 10 with the same seeds.
2. Observe the generation of gravel and sand near lakes and rivers on both devices.

Observed results:

The generation of sand and gravel on the devices is different. 
On android, gravel replaces sand (and sometimes earth).

Expected results:

Sand and gravel generation should be the same in the same versions and on different devices.

Image:

Windows 10

Android

Windows 10

Android

Windows 10

Android