DE classes at my school are taught by certified teachers by the university the credits are originally from. For example, DE Calculus is run through Harrisburg University, but the DE Calc teacher at my school is certified and also teaches precalculus and algebra 2. While the credits are earned through Harrisburg, they are transferable to pretty much any college/university in Pennsylvania and many other institutions in other states. In order to receive credit, I must get a C+ or higher in the class, and if transferred, the credits will show on my college transcript. That is just how my school’s DE classes work though.
DE at my school covers the topics taught in AP but is slightly slower and taught in a better way, in my opinion, at least for calc. Most people that have taken AP classes agree that the questions are usually worded weird or the question does not match the answer Collegeboard is looking for. For DE, the teacher makes all the tests and formulates all the questions themselves. If I took AP Calc, I would have a difficult teacher + confusing questions CB makes, but with DE, I have a great teacher who teaches well and the questions, while difficult, will be straightforward.