Even if there is a difference between them, it is very slight.
Literal
Both-parties [possessive-の] between [in-には], even-if existed [concessive-としても], difference [topic-は] very-slight is.
あったとしても (even if there is) uses the past conditional + としても. 相違 (difference) is a formal synonym of 違い. ごくわずか (extremely slight) quantifies the smallness. The formal register and hedging are characteristic of academic or analytical writing.