right away | right away immediately
Oneimpliesimmediatefuture,theotherimpliesthepresent.马上means"rightaway".TheBritishEnglishequivalentis"straightaway".正在means"rightnow".Ishouldqualifymylastremarkbysayingthat"rightnow"canmean马上accordingtocontext.IfIaskasubordinatetodosomething,andthepersondallies,Imightaddanimperative,"Rightnow!"Otherwise,ImightsaytosomeonewhoaskswhatIamdoing,"RightnowIamtypingonthecomputer."
One implies immediate future, the other implies the present. 马上 means "right away". The British English equivalent is "straightaway". 正在 means "right now". I should qualify my last remark by saying that "right now" can mean 马上 according to context. If I ask a subordinate to do something, and the person dallies, I might add an imperative, "Right now!" Otherwise, I might say to someone who asks what I am doing, "Right now I am typing on the computer."