Eurostar and other trains in Belgium

we can get a train into Brussels/Midi directly from the airport, and from there a train into Bruges without needing to purchase tickets in advance.

That's right.

I'm not finding anything about needing a senior rail pass like we would need for that discount in England. Do we just show our passports for proof of age, or am I missing something?

It's the honor system.; they will only ask if you don't look the part

I'm assuming Brussels to Paris isn't quite as complicated--Eurostar website says arrive 20 minutes early--but is that really enough time? Is an hour too much?

It's definitely nowhere near as complicated. There is no passport control (whereas with Eurostar between the UK and France you have to be there in time to do both entry passport control and exit passport control).

You might give yourselves 30 minutes, but that would just be to make sure you found your way in the station.

An hour would be way too much.

Thank you both. Sometimes things that seem simple really are so.

There are also direct trains from Brussels Airport (Zaventem) to Bruges. Time-wise it doesn't make a real difference.

that train between Brussels and Paris has recently been rebranded to Eurostar after the Eurostar company merged with the company running what was then called Thalys. Eurostar on the outside, Thalys under the skin.

It is a little confusing because the two arms, the trains between London and France and Belgium (up to the Netherlands), and the high speed Netherlands - Belgium - France, work very much as they did before the merger.

Same name, two methods of work.

With the London Eurostars it is very much 60-90 minutes ahead because of the security and border checks. The former Thalys Eurostar has none of that. You have a reserved seat in a particular car of a fairly long train so it is worth it to see where your car will stop so you can be in the right place, but that's about all. I'd probably be there 10 minutes before departure time.

Happy travels.

Almost all the local Belgian trains stop at all three downtown Brussels stations, same fare for any of the 3. I think there are only a tiny handful of direct trains from BRU to Bruges, and I wouldn't want to fuss to get one.

https://community.ricksteves.com/travel-forum/belgium/tricky-belgian-set-up

There are direct trains from the Airport to Bruges at least once an hour.

In Belgium, like in most of Europe you buy tickets for a route. So you do not buy a ticket for the 16:24 from the airport to Brugge. You just buy a ticket "Airport to Brugge" valid for a particular day, and that allows you to make one trip on that route, by any trains that serve the route. So wether you take the direct train, or change trains in Brussels is up to you. The direct train is convenient, but only runs once an hour. If you are ok with changing trains in Brussel Noord you add another couple of options per hour.