Sentai (Japanese: 戦隊), the Japanese word for task force (literally fighting team or squadron - Sentai was also a term used for Japanese squadrons in WWII), is most commonly used for classifying the "superhero team" genre of shows produced by Toei Company Ltd. and Bandai, and aired by TV Asahi. The shows are of the tokusatsu genre, featuring live action characters and colorful special effects, and are aimed mainly at families. (Wikipedia)
Power Rangers is an ongoing saga of television series about the epic adventures teenagers or 20-somethings who transform into the titular superheroes. The show is directly tied into a vast merchandising empire largely owned by Japanese toy company Bandai.
While the concept is based on the Super Sentai series of yearly serials, it is not an English dub of the original, but rather a 'new' production with English-speaking actors spliced in with the original Japanese footage to varying ratios. Due to the very Japanese nature of many of Sentai's stories and design, the American shows are always at least slightly changed to fit a Western audience. (Wikipedia)
This category contains toys from both Sentai and Power Rangers genre.