No difference in meaning at all.

Redwolf

As others have stated above, no difference in meaning, but I think the ort versions are the preferred form in the North (somewhat similar to Scottish Gaelic), whereas the duit/dhuit versions would be more common in the West and South.

_________________
[hr]Múinteoir Gaeilge - Irish Teacher[/hr]
My "specialty" is Connemara Irish, particularly Cois Fhairrge dialect, but I can also speak Ulster and Munster Irish with native-level pronunciation.
Is fearr Gaeilge ḃriste ná Béarla cliste, cinnte, aċ i ḃfad níos fearr aríst í Gaeilge ḃinn ḃeo na nGaeltaċtaí.
Gaeilge Chonnacht (GC), go háraid Gaeilge Chois Fhairrge (GCF), Gaeilic Uladh (GU), Gaelainn na Mumhan (GM), agus Gaeilge an Chaighdeáin Oifigiúil (CO).

Is there any down side or anything I should know about these two translations?

Tha gràdh agam ort
and
Tá grá agam duit

Are the accents correct?

They are for the Irish. I don't know Scottish Gaelic, so I'll let someone else answer for that one.

Redwolf

Accent marks go in opposite directions in Irish and Scottish Gaelic.
So the first one is Scottish Gaelic as Caomhín said -

_________________
___________________________________________________________

It is recommended that you always wait for three to agree on a translation.
I speak Connemara Irish, and my input will often reflect that.
I will do an mp3 file on request for short translations.
___________________________________________________________

Yes: Tha gràdh agam ort

_________________
I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

Thank you all so much! I really appreciate all your help. If I can, I'll post a picture of my tattoo when it's done.