It's one of those "It depends" questions. Depending on the colours, you may find different fixtures are close enough, but not always. To take an extreme example, there's no way that a budget "bowl of M&Ms" RGB par can will match say a colorsource PAR on very much at all, let alone subtle shades like gold tints, pale blues, straws, pinks, even whites will look off. But it's entirely possible that, especially at the less expensive end of the market, different manufacturers will have bought in the same emitters and just packaged them differently (sometimes even just bought in entire fixtures and badged them) so they'll be close.