Different non-fortified, non-dessert still red wines using different grapes taste about as different as raspberry, cherry, blackcurrant (cassis) and blackberry juices taste from each other. They're all recognizably wine, but the fruit flavours, tannin, acidity, sweetness, oak and mouthfeel varies quite a bit.

Cheap house wine from an open bottle at a bar or restaurant without a wine list can taste pretty similar between bottles. These wines are typically industrial product made in large vats where the wine itself, excluding taxes and everything else, costs a fraction of a dollar. If the bottle has been open for a day, the wine loses most fruit flavours, and structurally cheap wine is pretty similar - not very tannic (it's not usually a crowd pleaser), probably has added sugar.