From what my local dealer says, there is no difference for 2018. Its simply a carry-over. Low sales at the original MSRP and oversupply lead to the 50% price drop. They need to clear them out.
Someone else's words, not mine. I'd be inclined to think "why not just sell them as 2018s?"
I was going to buy one, but ended up with a Stromer ST1 2016 leftover for a similar price. That year ST1 has a very simple LCD display and I would much prefer the COBI, and one of my worries about the Urban Plus, was that the COBI system could be an issue.
If you haven't found my thread on my purchase process, its here:
https://electricbikereview.com/forums/threads/radcity-vs-haibike-urban-plus.16042/ I test rode the Haibike a couple times.
With the disclaimer that Haibike has on their warranty, I would only buy one with a local dealer support, which meant an 8% price increase for sales tax, too.
If there was a way to test ride a Juiced CCS nearby, I would have been happy to compare that vs the Urban Plus, but that wasn't possible. Similar price point, one with lower end components and more power, the other with a more "German fit-and-finish." It would be like an American hot-rod or sports car vs a German GT car - but for bikes. Would have been a fun comparison.