Period vs. Implantation bleeding


So, I’m just wondering the difference between a period and implantation bleeding. I’m thinking I may be pregnant since I’ve been nauseated for three days and I can’t get enough to eat, but I just had what I believe is my period last week. My husband and I have been trying to conceive, so I’m just trying to figure out if I need to take a pregnancy test now or wait until I’m due for my next period.