Implantation bleeding or period

J

Anyone know how to tell the difference? I had my coil removed 20th July and had a period 13th August and have a slight bleed today no cramps etc but the app is now saying I would've ovulated later than we initially thought going by the current cycle if today is an actual period. So I don't know if today is a period or potentially implantatin bleeding?? Took pregnancy test yesterday which was negative??