While there are some similarities one could draw between Camilla and Wallis, they are really only similar if one looks at Charles and Camilla using history’s eyes and morals.
Divorce itself is extremely common place these days, and Charles himself is technically not a Divorcee anymore, he’s a Widow. Further, both the Church and Government have “grown” with the times and given that not only was it extremely unlikely that Charles and Camilla would have children, but had been specifically pointed out that if they did, such Children would NOT be in line for the Throne, it really just comes down to more of a “who cares?” if they marry.
Lastly, MOST Royal Marriages are handled (believe it or not!) by Law. Specifically, (at that time) the
Royal Marriages Act 1772, which was followed to the letter when Charles and Camilla were married. Further, the Church clearly had no objections as not only was there a “Blessing Ceremony” after the civil wedding, but Rowan Williams, the Archbishop of Canterbury publicly stated “These arrangements have my strong support and are consistent with Church of England guidelines concerning remarriage which the Prince of Wales fully accepts as a committed Anglican and as prospective Supreme Governor of the Church of England.”