The biggest difference between Huawei P40 & P40 Pro is that the P40 Pro adds another camera along with greater capabilities.
The core P40 model sticks with a triple-camera setup on the back with 50MP SuperSensing, 16MP ultra-wide, and 8MP telephoto cameras, delivering 3x optical zoom and 5x hybrid zoom, as well as 30x max zoom.
While in the P40 Pro you get 50MP SuperSensing, 40MP ultra-wide, 8MP telephoto, and time-of-flight sensors that give you 5x optical zoom, 10x hybrid zoom, and 50x max zoom.
So if photography is your choice I suggest you P40 Pro.
For more:
https://www.xcite.com.sa/phones/mobile-phones/huawei.html