According to what I have found, studying at a Fachhochschule is more job-oriented and practical instead of theoretical.
The followings are from my direct experiences (I got a B.Eng. Maschinenbau from the FH Aachen, but also spent 3 semesters at the RWTH Aachen):
At a Fachhochschule (FH), most subjects require students to complete a Praktikum as a pre-requisite for the exam. Students have to work on hands-on tasks, document results, write a report, and then submit it to the TA or directly to the professor.
At a Technische Universität (TU) or a normal Universität, chances are you only learn theories and take exams. Some professors might offer an excursion with very limited spots to one of his labs, but you can only stand and watch, which IMO is useless.
At a Fachhochschule (FH), subject contents are not as broad as those at a TU, but everything that is taught in class will be asked and tested in the exams. Exam questions require you to apply your knowledge to specific situations. None of them ask you to prove a formula.
At a Technische Universität (TU), contents are, let's say, 150% of those taught at an FH. You have to learn everything, even those that won't show up in the exams. Exam questions are a mix of applying knowledge and proving the theories.
Furthermore, the FH Aachen's curriculum also requires students to complete 2 project-based subjects called Projekt 1 and Projekt 2. In Project 1, every student is divided into groups and each group receives a task from a guest, which usually is a local company, and within 1 week they have to work in teams to come up with solutions and each team has to present the solutions in front of the rest including a group of professors and one jury from the company. Project 2 is a bit more independent. Students are free to organize their own groups, but this time each group receives a task from the university. These tasks could come from the projects that current Ph.D. students are working on, and they have around 3-4 months to solve the problems. When I took part in these projects, almost every fundamental concept and skill that I previously learned was brought to use. These are mechanics (all three), materials, thermodynamics & heat transfer, electrical engineering and electronics, fluid mechanics, and 3D CAD & simulations. This kind of activity is not offered at the RWTH.
Lastly, to your question about a degree from an FH, it depends. According to Stanford's eligibility for graduate admissions, Germany's three-year Bologna-compliant bachelor’s degree is accepted. UCLA, on the other hand, explicitly says that Holders of the Vordiplom, Zwischenprüfung, Bachelor/Bakkalaureus, or a diploma from a fachhochschule are not considered for graduate admission.