Yes, there is no difference in Lord Nitai and Lord Gaura. However, Vrindavan das Thakura explains in Sri Chaitanya Bhagavata that Lord Nityananda is even more merciful than Lord Chaitanya. Just see the Jagai Madhai pastime. Lord Chaitanya was going to kill those 2 rouges, but Nitai decided to save them.
Qualitatively, however, there is no difference. If one accepts Nitai without Gaura or Gaura without Nitai, then one will be practicing ardha kukuti nyaya, the philosophy of half a hen. Such a person is eternally condemned.