No shouldnt look much different at all. The space between the two openings should be really small. In a male the space is much larger. The "balls" (sorry :lol
will be really visibile from 5/6 weeks onwards and depending on the colour of the gerbil, they in most cases are dark (lighter colour gerbils like PEW/REW will still be light coloured.
If you are struggling to tell the sex of an adult gerbil then its fairly certain its female!