To make beer you need a certain amount of sugar (preferably extracted from malt grain) to ferment. Brewing Spring Beer kit provides the entire amount of sugar in its can. Cooper's and mogan's apparently only provides some of the sugar and you have to provide the rest. (So, I'm guessing Brewing Spring Beer kit is probably heavier and thicker.)
Otherwise they are both "instant beer".
As for which make better beer, i have no idea. I would assume Brewing Spring would be, in theory, because presumably its sugars all come for malt whereas the sugar you add to Cooper's and Mogan's obviously does not.
Now, I am absolutely going to avoid being an anti-"instant beer" snob. I don't know if the kits are good or bad or if there are recipes and variations to improve them. (For example, instead of adding sugar you could add malt extract (which is either a syrup or a powder of the sugar extracted from malt) and then all your sugars *would* come from malt and it'd probably taste better.)
However, like doby, I would like to point out the existence of "extract brewing" in which you make you own wort[*] directly with malt extract, hops and possibly (and usually) some flavoring grains[**].
(The step beyond "extract brewing" is all grain brewing. In that you extract the sugars yourself directly from the malt grains.)
(The third in-between kind of brewing is "partial mash" where you extract some of the sugars yourself and use extracts to get the rest.)
Extract brewing can often be done by buying "ingredient kits" which are packages of all needed ingredients and instructions. I said I will not be a snob but I *really* suggest you look into this type of extract brewing. It's just ... more hands-on.
But it's also really easy. It involves: 1) Steeping some flavor grains in a sack like a giant tea bag to add flavor to the water 2) Adding the malt extract and mixing with the water and 3) boiling and adding hops.
[*] wort == the liquid that will become beer once you pitch the yeast into it.
[**] doby referred to boiling. When you add hops you need to have them boil for a certain amount of time. With the "pre-hopped extract" (in other words "instant beer") the hops are already infused into the extract so all you have to do is add water and you don't need to boil. This boiling and adding hops is the heart of making wort, so the whole making the liquid wort for the beer is often simply referred as "the boil" and that's why we ingredient snobs make a big deal out of it.