The discrepancies arrive because of the definitions of who was killed and for what reasons. For instance, not only were Catholics killed by Elizabeth, but also Presbyterians, Anabaptists, and other dissenting Protestants who were not Anglican. Whether to count people killed in Ireland and Scotland affects the numbers; also whether people killed incident to rebellions are to be counted, whether they were armed rebels or unarmed civilians (hard to make a distinction, when so many of the rebels themselves are only armed with scythes, axes, pitchforks and kitchen knives.)
I wouldn't want to counting up the awful totals for either one of them.
In fact the total number of religiously-motivated executions under Elizabeth was in the same league the same as under her sister Mary, and the number of penalties of all kinds - death, imprisonment, fines, pillorying - was very much greater under Elizabeth --- who also ruled far longer. I think it's fair to say Mary is remembered as "Bloody Mary" not because she was more bloodthirsty than her half-sister who executed her, but because she was unsuccessful in establishing her monarchy; and history is told by the winners.
We can be grateful to say goodbye to those terrible days.
Actually, I think Mary her half sister died of illness. Will have to check on that. Bloody Mary was the half sister. Elizabeth did execute her cousin Mary Queen of Scots after a long imprisonment.