My info is very old, but since no one else has answered, I'll start:
As far as general Physics, the ratings (MM, EM, or ET) receive the same amount of training. The level of the course is on the high school level or non-physical science/engineering level in college (i.e., not calculus based). However, there is a nuclear engineering component which is not covered in lower division physics courses, although it is not as rigorous as nuclear engineering/physics courses on the upper division level. (I have never taken an introductory, lower division nuclear engineering course, so I am not familiar with what would be covered.)
When I went to high school, calculus was not offered and any student who met the prerequisites had to go to a nearby college to take the course. It seems that calculus is now commonly offered as part of the high school curricula and I would guess that the math in Nuclear Power school gets to that level. For example, no "delta/epsilon" stuff, no series expansion ... I don't think it even gets as far as the chain rule, but I could be wrong about that.
Keep in mind that the minimum required for entry into the nuclear power program is one year of high school algebra. Everyone in nuclear power school is supposedly taught at the same level, and it isn't possible to get the bottom of the class to a high level in six months. Unlike the typical college, where a course might be taught to the mid-level student, the aim of Navy training is to get all students to pass. At one time, students with higher aptitude were grouped together and might be given a bit more material to keep them interested, but that was many years ago. Now, the classes have students of all abilities (perhaps so the students can help each other out) so everyone is taught at the same level.
Still, if you want to excel, there is plenty of material to keep you interested as long as your goal is to learn as much as possible, rather than just learning the minimum to pass. When I went to nuclear power school, I was in one of the higher sections (when students were segregated by aptitude), and our section had no mandatory study hours, except in the last week. However, I spent more time in school than anyone in the lower sections with mandatory hours because I wanted to learn the material. I could have spent no extra time and still passed. What I'm trying to say is that if you really like physics and math, there is more than enough material to keep you interested during your time at Nuclear Power School, regardless of the level of material on which the material is taught. However, you have to be self-motivated because no one is going to encourage you or give you extra credit for reading material that is not covered in class.
I do NOT encourage you to go to outside sources, such as college texts in nuclear physics and nuclear reactor engineering until after you finish with nuclear power school because while you are there, the Navy wants you to learn things in a specific way and with particular application to Naval nuclear reactors. Incorporation of concepts from outside sources will likely be harmful to your evaluation because the Navy wants things answered in a particular way and if you say something they don't expect, no matter how accurate it might actually be, it might be considered to be a "wrong answer".
I don't know anything about STA-21. Physics should qualify as a "technical degree". I would guess that the interpretation of "technical degree" is a "hard (i.e., physical)" science or engineering major.
