Season 2 starts tomorrow, September 14th, at 16:00 CET. The most significant new mechanics have already been introduced , and in addition to that there will be some adjustments to existing mechanics and production methods.
The new management point system is meant to encourage the construction of more numerous but smaller buildings, which other than diversity in the game helps stabilize the economy and reduce the need for micro-management of production. In the interest of moving further in this direction, the cost and impact of building upgrades will be reduced in a few places.
Production methods using bellows will now
consume a small amount of the corresponding product
The bellows (bloomery, coppersmith, foundry and smithy), spinning wheel (spinnery) and treadle loom (weavery) upgrades are getting a lot cheaper, and the production methods using them will start requiring the new products bellows, spinning wheels, and looms. This is similar to how the grindestone upgrade already works, and helps spread out the cost of these high level production methods in time rather than during the construction of an expensive upgrade.
The new machine workshop produces advanced
machinery
A new building, the machine workshop, is added for producing spinning wheels and looms, while bellows are made at the existing leatherwork
Manual and automated travel distance is harmonized and extended. The automatic trade range is technically unchanged, but trade routes will now allow partial trips if the movement points aren’t divisible with the journey length (a common case) instead of rounding down. This can give significant added capacity in many cases, and more incentive to optimize trade route length.
New manual ranges:
The cog and hulk are getting marginally cheaper to operate, and shifting some cost away from labour to other inputs.
With commoners now being price-sensitive and dynamic in their sustenance spending, it opens up for them consuming more diverse products.

They will now pick from a range of product to satisfy their various needs, adapting to local price and availability. Pasties, flour, charcoal, (fresh) fish and meat, and honey, have been added as sustenance options since season 1.
The 0.75% prestige decay has been replaced with a 0.5% conversion to legacy, essentially making it 1/3 cheaper to sustain prestige. Prestige received from building production methods is reduced a bit and the cost of the prestige buildings increased, to partially (but not fully) compensate for this.
Additionally, the cathedral gets doubled (twice the cost, production throughput and prestige).