I'll confine these comments to the 15" 15 hole W201 and W124 wheels.

Whilst the W201 and the W124 wheels look similar, they are of different width.

W124 wheels are 6.5" wide, W201 are 6.0" wide.

W124 wheels and 195/65 size tires will work on a W201.
I cannot see why a 6.0" W201 would not work on a W124, it just looks a bit different.

There is a noticable difference in the rim edge/spoke profile.

To add a bit more variance, the 1989 and up wheels are cast, not forged.
You can tell by the radius of the corners in the 15 holes. Greater radius=forged.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles