Agreed with Alf...
You must get the proper seals.
It is very important to operation of the engine.
Frequently, they won't even start with worn seals.
rc
First off those two seals will fit, the only difference is in the thickness, one being 3.8mm and the other being 7.5mm. The crankshaft and clutch seals have different diameters and different shaft size, so no you cant swap them.
Crankshaft (14.8mm diameter shaft) seal.... 14.8mm X 27mm X 3.8mm (enough room for a 7.5mm)
Clutch shaft (15mm diameter shaft) seal...15mm X 35mm X 7mm
If both seals had the same (outside) diameter you couldn't use a 15mm seal on a 14.8mm shaft...it won't seal and you will have both a compression and/or vacuum leak. Although I think you could use a 14.7 mm seal over a 15mm shaft, but it would be tight and excessive seal wear might occur.