Of course there is a difference. How so? All the wine kits we sell are made from grapes – reds, whites and roses.
Both contain various acids, tannin and sugar in varying degreees.
Commercially, all grapes are crushed then pressed for the juice. And most importantly almost all grapes have clear "meat, flesh". A few purple/red grapes do have red meat. The difference are these:
When making white wine, the maker will crush the grape and press them immediately. Wishing to make a red wine, the maker crushes and then press 2-3 days later. That way, the skins will have leached their tannin and colour into the juice.
How else would one get a White Merlot and a deep red Merlot from the same grape?
What is a rose? Simple: a white wine with 3-4% red wine added.
What is pomace? All it is is the skins from grapes after pressing. These are dried and used for certain industries and home winemaking (ex strawberries) where the tannin content is low. The rest? Fertilizer!