only - únicamente, solamente just - solo, justo - just a minute - solo un minuto just one time - solo una vez solamente una vez - Only one time/once justo a tiempo - just in time

Only can be translated in Spanish as sólo, solamente, único, únicamente: I only want a sandwich for lunch. -- Sólo quiero un emparedado para almorzar. It'll only make things more complicated. -- Sólo hará las cosas más complicadas. She was the only girl in the class with red hair. -- Ella era la única chica pelirroja de la clase. Just is translated as justo, apenas, and also as sólo (only, merely): I just want a straight answer, nothing more. -- Sólo quiero una respuesta directa y nada más. He just missed the bus. -- Justo se le pasó el autobús.

1.I just want to get some water. 2.The only choice we have now is ... The only has more emphasis. XD

thank you very much