Deore is a few steps above (nicer) than Acera in the Shimano mountain group hierarchy. Having said that, it's hard to know if there will be an actual difference in performance without knowing the part numbers of the derailers. They may be switching from a traditional Deore to a Shadow-series Acera, which some might consider to be at least as good, depending on your intended use (Shadow-series derailers have stronger springs and better chain tension with less of a tendency for chain slap).

Regarding the crankset and the cassette, the 2019 model has a wider range than the 2018 model. The 2018's lowest/slowest gear was a 28 in the front and a 32 in the rear (a ratio of 1.14:1, or 1.14 revolutions of the crankset for every 1 revolution of the cassette). The 2019's lowest gear is a 26 in the front and 34 in the rear (a ratio of 1.31:1). This is a reduction of about 15%, which means you can climb steeper hills easier. The highest/fastest gear did not change...both bikes are 48 in the front and 11 in the rear, or a ratio of 0.23:1, meaning that the cassette turns about 4 times for every 1 revolution of the crank.

If the brakes are similar between the two, and if the frame geometry is the same, then I probably prefer the 2019's specs over the 2018's.