Pharmaceutical Engineering involves the application of Engineering, Technology, Scientific and Mathmenatical principles to the Pharmaceutical Industry.
I can not say whether it is as difficult as a pharmacy major because I am not a pharmacist. I am a chemical engineer who has worked most of my career in the Pharmaceutical Industry (21 years now), so in a practical sense I am a Pharmaceutical Engineer.
What I can say is that the conferring of a degree in Pharmaceutical Engineering is relatively rare, especially in the US and at the undergraduate level. That is changing, though and we may see more BS programs as the field evolves as a discipline.
It would probably involve studies in Biology, Chemistry/Biochemistry, Statistics and Pharmacology, along with more traditional Engineering coursework.
To more directly answer your question "more difficult' would depend on the student and where his or her skills lie.
