England Remains Catholic

[Verily]

America: Probably more colonies advocating religious freedom and Protestantism. There simply would have been a greater need for it. Perhaps Massachusetts, Pennsylvania, and a few others embrace Puritanism as simply an anti-Catholic protestantism. Thus America still has a protestant background, but has far more Catholics than today.

Assuming that something resembling the United States ever comes into being (doubtful, IMO), I think it quite likely that it would be far more Protestant today rather than less (or at least more Protestant as of 1920 or so, hard to say after that), and probably not a particular economic power or spanning the continent. Hostility towards Europeans Catholics would have been greater due to England being Catholic, and America would have taken a much harsher line against immigration by "Papists".

[Verily]

Ireland would still be British. My estimates have the island with between 6 and 24 million residents.

As well it's colonies would have seen a 75-25 split the other way. IE the US would not be 25% Catholic, it would be 75%.

Tensions in Ireland were not cause by the religious difference in the slightest, although religion became a convenient way to delineate who fell on which side and eventually a source of bigoted stereotypes and slurs. Partitioning Ireland would have been much more difficult without religious statistics, though, and it is therefore possible although unlikely that Ireland would be united and independent.