I do not know enough to contrast the two parties in detail although the differences seem superficially anyway both historical and regional.  DUI is also much larger than DPA (almost twice as large).   It seems from a historical context that DUI is more radical in terms of Albanian autonomy, and DPA more open to integration, but that is only a educated guess looking in from afar.  Also over the last decade or so, DPA seems more historically linked with centre right parties and DUI with centre left ones.

Wikipedia likewise has a good article on the DUI here.

Democratic Union for Integration
The Democratic Union for Integration (Bashkimi Demokratik për Integrim, BDI, Demokratska Unija za Integracija, DUI) is the largest political party in the Republic of Macedonia among ethnic Albanians, and the third largest political party in all of Macedonia. It is led by Ali Ahmeti. The DUI is the successor to the Albanian National Liberation Army, which fought the Macedonian security forces in 2001. As a political party it was formed 3 months before the elections in June 2002. The DUI held its first Congress in November 2005.
At the legislative elections, 15 september 2002, the party won 11.9% of the popular vote (70% of the Albanian vote) and 16 out of 120 seats.
From 2002 to 2006 it was part of the ruling coalition along with the Social Democratic Union of Macedonia and the Liberal Democratic Party. At the last legislative elections, held on July 5, 2006, the party's size increased slightly. It received 12% of the vote and 18 seats. Due to the defeat of the Social Democratic Union, it is currently not certain whether the Democratic Integration Party will participate in the next government.

I like the silence of a church, before the service begins better than any preaching. ~Ralph Waldo Emerson