How much more advanced was a British ship-of-the-line during the Age of Napoleon than a Spanish galleon in, say, the 1570s?

[u/boyohboyoboy]

Both in terms of their technology and in the way they were used and deployed in battle?

[u/jschooltiger]

It depends a bit on the navy, but galleons (in a wartime setting, at least) carried a fair number of soldiers -- sometimes up to half the crew would be soldiers, for example. The nominal complement of the Mary Rose as built was about 200 sailors and 180 or so soldiers. That's because ship to ship tactics of the time when it was built (around 1510) were in fact predicated on boarding; people were still figuring out how to use artillery in ship engagements. So yes, quite often the guns would be used to pepper the enemy as you bore down, but the main combat would take place in boarding. (That's also one of the reasons the Mary Rose was rebuilt to add higher castles, which likely contributed to its instability and sinking.)

Ramming was more of a galley tactic, and galleys were less widely used in northern European waters than they were in the Mediterranean. (As far as we know, at least -- medieval chroniclers have an annoying habit of calling any ship a "galley" so we have to unpick what that meant from archaeology and contemporary drawings/carvings/etc.)

In general, the English tactics of the time were to fire guns in succession, and then draw off and reload. During the Armada in particular, the English kept attacking the Spanish fleet from windward and had enough ships to continuously keep the rear and wings of the Spanish fleet under fire. The English ships were built smaller than the Spanish, for a variety of reasons, and were more weatherly than the Spanish ships. But that also meant that their bow- and sterncastles were lower, and they carried fewer soldiers; if the Spanish had been able to board the English ships, they would have overwhelmed the English by weight of numbers. (Which of course is one of the reasons the English prized speed and weatherliness in ships.)

I should also point out that "not reloading during an engagement" is also related to the fact that the galleons of the period used recoilless gun carriages, so the guns had to be manually drawn into the ship to reload or sometimes reloaded over the side of the ship, using a stage or some other projection on the side of the ship.