TYM (Korea) makes Mahindra, RK, Branson, and also TYM-branded tractors. The price differences you're seeing may simply be the different pricing strategies you'd expect between more established companies like Deere and Kubota vs "up and comers." There may or may not be important differences between the actual tractors.
Well-known companies with longstanding reputations (deserved or not) such as John Deere and, increasingly, Kubota can market themselves as "we're the best" and therefore can charge more. To complete with this, less-well-known brands ("up and comers") may adopt a "better value for your money" strategy, thus the lower prices.