A junior high school (usu. 7th-9th grades, ages 12-14) was AE only, as far as I know, and is now dated anyway, since most are now called middle schools (usu. 6th-8th grades, ages 11-13). It is not a degree- or certificate-granting school, just an intermediate level between elementary and secondary that doesn't really exist in German-speaking countries as far as I know. Unlike a Realschule, its classes are not usually sorted or specialized by interests or topics at all, because like other US schools, it runs on the Gesamtschule concept, including both academic and non-academic students. (The exception would be a magnet school, designed to attract students with special interests like art or music; but those are usually high schools.)
Vocational (high) school also seems wrong, because it has the connotation of completely non-academic -- that is, preparing students for practical jobs involving manual labor, like construction, carpentry, plumbing, auto mechanics, cosmetology, lower-level nursing/caregiving, lower-level kitchen work ... I would guess that that would be more like a Hauptschule.
If I had to describe a Realschule from an AE perspective, I would try something like ...
career / business high school
semi-academic high school oriented toward business and practical careers
BE sources suggest that 'secondary modern' could be a loose equivalent.
Anyway, all these years later, I still firmly agree that 'junior high school' was never right and should be replaced. I would suggest just reading some Wiki entries in both languages, if nothing else.
This really needs to be changed, however belatedly.