Is vipassana practice the same as insight practice? Are the terms completely interchangeable? I know there is the vipassana movement but this appears to be Theravadin so it makes me think that vipassana only applies to Theravadin Buddhism? However I'm sure it's broader than that - our vipassana wiki says it is if that is anything to go by.
They are synonymous. Insight is in fact the word that is used to translate the word Vipassana.
All schools of Buddhism that talk about meditation talk about Samatha and Vipassana (but of course they'll use the sanskrit names Shamatha and Vipashyana, or their translated terms 止 観 (Chinese Zhi and Guan, Japanese Shi and Kan) or in Tibetan shiné and lhatong. They understand the meanings of these somewhat differently but no one has a monopoly on any of them.
The Vipassana movement is a particular trend of Buddhist meditation that started in Burma in the 1800's and encompases several traditions (Mahasi Sayadaw, Goenka, Pa Auk Sayadaw, etc..) and they are called the Vipassana movement just because that is their primary emphasis. But other traditions have it too, even though they might very well use very different sounding language to talk about it and have different meditation methods.
Prajñā is often translated as "wisdom", but is closer in meaning to "insight", "discriminating knowledge", or "intuitive apprehension".
jñā can be translated as "consciousness", "knowledge", or "understanding."
Pra is an intensifier which could be translated as "higher", "greater", "supreme" or "premium", or "being born or springing up", referring to a spontaneous type of knowing.
Vipassanā (Pāli) or vipaśyanā (विपश्यना, Sanskrit; Chn. 觀 guān; Tib. ལྷག་མཐོང་, lhaktong; Wyl. lhag mthong) in the Buddhist tradition means insight into the true nature of reality, namely as the Three marks of existence: impermanence, suffering or unsatisfactoriness, and the realisation of non-self.