I have looked into this from the beginning, so here's the answer:
The old (current live) system worked like this:
Equipment Writs (jewlery, blacksmith, clothing, woodworking) gave a base exp of 16840.
Consumeable Writs (enchanting, provisioning, alchemy) gave a base exp of 11227.
The current PTS system basically updated all writs to give the same base exp, which is what they referred to as ''max exp''. This max exp is equivalent to literally exactly the equipment writ value.
TLDR: All master writs now give 16840 exp rather than 16840/11227, which is a massive buff for alchemy/enchanting/provisioning writs, since despite being a 50% lower exp yield, were still basically the fastest way of grinding exp in the game ignoring money costs.