Postures or stances (kamae) are roughly divided into "Upper level" (Jodan), "Middle level" (Chudan), and "Lower level" (Gedan). In kendo and some schools of iaido these are also the names of the actual kamae, but other ryu have different names for the specific postures within each group. Seigan, raito, in-no-kamae, etc.
Two different ryu may have different names for the same posture, or use the same name for different postures. It can get rather confusing when reading about different schools' methods, or trying to visualize a narrative from a samurai story, but if you're in training and your sensei uses Japanese terminology in class (which I think should always be the case) you pick it up pretty quickly.
Yours in Budo,
---Brian---