Deepin is base on Debian sid .

Deepin is quite different with Ubuntu, especially for Chinese.

linux deepin can use deepin-appstore。There are lot's apps for Chinese people, include Android apps and Windows Apps.
deepin-wine is a good solution to run Windows Apps。Most Chinese Apps are build in appstore.

As far as I could understand March update posts on the site, Deepin is no longer based on Debian sid, it's using stable branch (currently that's D9 "Stretch", and D9 is already at 9.8 with D10 planned for near future).
Ubuntu on the other hand is based on Debian's "testing" branch (so currently that's closer to D10 "Buster"). In both cases repos are synced with Debian's and undergo further investigation/curation before being shown/exported to the end user of respective distros.  
As such, "testing" branch has a lot newer versions of software albeit in some cases less tested as well. Sid, also known as "unstable" branch of Debian is offering even fresher revisions to binaries and sources but at the price of less extensive tests (though whether it is currently really unstable or not is less apparent than years back, but Deepin is dropping the sid branch in favor of the stable though more stagnated branch). This being said, you can eaily see that a lot of current D10 or D9-backports packages already present and used in Debian or *buntus are more fresh than those offered in Deepin repos. The disparity might grow further apart once the D10 is officially out and "testing" starts being populated with even newer packages, while Deepin is, as stated in news, to be rebased on "stable". Whether the stable D9 branch gets switched by Deepin team to the new D10 stable branch at that time is a question to the devs. Might be the Deepin 16 will allow for seemless "update" to the new "stable" but that again remains to be seen. At the same time *buntus are possibly going to be getting more and newer software though whether the dist-upgrade solutions would work well without DDE newest codebase updated to work with the new D10+ system packages is a matter of a question to the Canonical devs and community. But...
And here's the real "but" -  this distro is better prepared to handle Chinese market (cannot vouch for that but my friends from China say so...) and has better integrated select few apps due to repo packages and appstore being curated by the same devs.
That being said, it's not nearly like, but close to KDENeon vs Kubuntu comparison, where Neon is still based on the last "stable"/LTS release and newest Kubuntu using the short-term October release. Kubuntu (non-LTS) gets newer packages for the whole system, but KDENeon gets the bleeding edge KDE apps/platform (newer than Kubuntu) curated by KDE devs but remains at LTS's older package set for the rest of the system. Similarly, Deepin linux would net you better OoB DDE experience with fresher DDE code with less up-to-date rest of the system base, while *buntu might give you access to newer apps in repos at the expense of DDE somewhat behind and possibly more fragile to larger system updates.