Kanji for Squad

The two differ by size and by setting. 班 is a small working group inside something larger — the section or team you are assigned to. It is the word used for groups within a school class or a work rotation, and 班長 is the person leading one. It is organizational rather than military.

隊 is the larger and more formal unit: a corps, a troop, a party. 軍隊 is an army, 部隊 a unit or detachment, 自衛隊 the Self-Defense Forces, 隊長 the commander. It also covers organized non-military bodies — a rescue party or an expedition is a 隊.

Neither character is a word on its own in ordinary use, and neither has the informal warmth English “squad” has picked up. Both describe structure: who is grouped with whom, and under whom.