Historically speaking the Ilford fast films have had a bit straighter curve shape than TX on the high end or iow, more highlight contrast, but it's been so long since I've used any TX I have no idea if that's valid today. Ilford renames its films (HP3, HP4, HP5, HP5+) while Kodak just keeps calling its film Tri-X no matter what changes have occured over the years.(posted 8682 days ago)Personally I suspect anyone who sees any radical differences between TX and HP5+ is engaging in wishful seeing.