this is my first-ever post. thanks in advance for any help or opinions in response to my question:

I've used a mac of one kind or another as an artist for many years - but have always managed to not learn much about the technical aspects I'm in the market for a new desktop set-up. I'd be using it almost exclusively for 2D art / photo / graphic design.
I want the very best color rendition and resolution I can get but I really don't need anything super-duper otherwise.

I'm very confused in comparing all the different options. I stopped in best buy and started looking at stuff and the staffer told me that the best display option would be to buy a retina-display laptop and plug it into a Thunderbolt display - is that accurate? It did look very good, but there wasn't any iMac set up to campare that to. I couldn't believe that apple would require such a set up for optimal display. Wouldn't the imac the same display? or does the retina laptop have some special hardware that the thunderbolt display is taking advantage of?
sorry question is so long