If you are talking about buying a new Silver Pigeon, the major differences as mentioned, are ..
The Sporting is close to a pound heavier than a similarly configured Field model, usually just over eight pounds vs about 7 1/4. Adjustable comb Sporting models are heavier.
Wide target rib on Sporting, narrow rib on Field.
Centre bead on Sporting, none on Field.
Manual safety on Sporting ( preferred for range use), automatic on the Field.
Chunkier forend with finger grooves on the Sporting, slim forend usually with Schnable tip on Field.
The Sporting model is available with a left hand cast stock, the Field model generally isn’t.
The Sporting model is available with two different comb heights although the higher comb is usually a special order in Canada/USA. The adjustable comb is preferred here.
Butt stock slightly more chunky on the Sporting model and the recoil pad is larger.
Sporting Clays originated to simulate various hunting situations so a field ( hunting) gun that fits you well will work fine for Sporting Clays but as in most sports, specialization has optimized Sporting models towards range use. If you want to have fun on a sporting clays course a field gun will fill the bill however because these guns are comparatively light, if you put a lot of ammo through it in a day it may beat you up some, depending on fit. However if you want to be competitive, sooner or later you’ll move to a dedicated Sporting model.
Conversely the Sporting model can serve just fine for hunting but you will be lugging around an extra pound of iron all day. If you truly want to own just one good all round shotgun for field and range try to lean in the direction that is most important to you, someone else’s priorities may be different. Personally, having owned and used many Berettas of various models I prefer to have and use both but if I had to choose only one for all round use for everything I would go with a Field model, your choice may be different.