I agree with Linda Bell's answer. Jean and Jane interchangeable in Scottish naming and Jessie is usually another form of Janet although I think there are some cases of Jane being used for Janet.
There are quite a number of variations the usual Betty interchaning with Elizabeth, more often Betsy in earlier times and if going back to 16th century Isabel is often interchangable with Elizabeth.
Others are Nan or Nancy for Agnes, Giles becoming Grace, Meg for Margaret and so on. With male names Gaelic versions sometimes are shown by an English version. Iain being John, but in Scots Jock or Jack, Donald becomes Daniel, Sheamus is James. Alexander was a popular given name in Scotland (we had good kings of that name) and so there are numerable versions Alec, Sandy, Cy. George was less common but in Scots may appear as Dod especially in NE Scotland.