Well, Australia and South Africa become more significant as settler colonies, but the sugar is where most of the money was. Canada at the time was snow and Frenchmen, and we know what losing America did OTL... so actually not too much of a difference.
The main differences are going to be in American politics... the lack of a British threat to the North will have huge effects on the ability of the federal government to accrue power to itself.
This, albeit South Africa was still Dutch.
And otherwise, for Britain? It wouldn't change much. If... if at all, really.
For all the political anger at each other, economically, America was still very much tied to Britain until 1815 when it came out of the War of 1812 with a manufacturing base in the north that began to be built up. It also was still quite culturally tied to Britain and the northern USA was very Anglophilic. By adding what would be English Canada (*Upper Canada+Maritimes) will have at best subtle larger effects in the long run and only a small short-term boost to the north for now in area and population... and I believe Quebec would spin off into its own country post-Articles, so America won't be fundamentally different in its makeup past that larger north.
It's important to note QUITE THE MAJORITY of British America was lost to it in 1783, and the biggest remainder of BNA solidly French, so the vast majority of 'fellow Englishmen' were already gone (the Loyalist colonies not quite being settled yet in the immediate moment). We've probably seen the TTL reaction already in OTL because throwing in lightly-populated Canada and the Maritimes won't change reactions much in the short term, if at all.
But longer-term effects. Hmm. More Loyalists may go to Britain. Australia was proposed as a Loyalist haven in OTL by Joseph Banks, you may see New South Wales a mix of Loyalists and convicts a la the early Chesapeake colonies. As 19th century immigration occurs, the OTL British immigrants to Canada will still go to *Upper Canada, just that *Upper Canada happens to be part of the USA in this world. After all, the majority of British immigration to North America was actually to the USA so there's no reason for immigration tides to change at all. Britain will go on to capture most of the West Indies in the Napoleonic Wars, so there's no reason for butterfly effects there. Whatever troops stationed in OTL Canada will be attached elsewhere, but with the British army so small it won't matter much in the long run.
TL;DR: We already saw the majority of British America gone in OTL - the originally English-settled parts to boot - so slapping on the rest of North America in 1783 (then-empty Upper Canada, French Lower Canada, and barely-on-the-radar Maritimes) won't change much of anything if at all. Australia may become a mixed Loyalist haven-convict settlement. The small amounts of British troops stationed in Canada supplement British colonial ventures elsewhere but may not make a big difference in the Empire's fortunes in the long run. Britain and America bitch at each other politically as they get rich trading with each other as in OTL. Etc.