They have about the same amount of juice concentrate.
I haven't made any of the Weekday Wine kits, but 3 of my earliest kits were their Small Batch kits (to make 1 gallon of wine) to get my feet wet. I got the Cab, Merlot, and Pino. They don't sell them any longer, apart from being bundled with some equipment. I suspect it was the same concentrate as their Weekday Wine product, but only around 1 liter of juice instead of 5.5 liters.
So far, I'm not terribly impressed. I last tried some of them in late August, and after a little over 7 months, they still had a really strong, twangy flavor. I'll probably try them again sometime next month to see if they've improved at all.
By comparison, the Fontana Merlot and Malbec kits that were started a couple of weeks later than the small batch kits are actually approaching the point of respectability, and I'm guessing will be there within another few weeks.
Everyone's taste is different, and your mileage may vary, but for any future "cheap kits" I plan to stick with Fontana.