Thalys cost difference?

I bought Thalys tickets a couple of months ago. In my research I learned that there are a certain number of less expensive tickets and that once their sold, the price goes up. Maybe those less expensive tickets had already been sold for the earlier train?

I booked Premier. My reasoning is because there is less seats, there is more room for luggage. We need the luggage rack for our 25" suitcases. You also get a free meal with wine.

Good information; thank you!

Since the pricing is demand driven, More people want to ride the 2:43 than the 3:13. I imagine a large number are business or government types who don't consider price or have some kind of frequent traveler discount. And Economy is perfectly comfortable.

Thanks, Sam, and go Packers! (We're originally from WI)

Is there any truth to luggage accommodations being different? We will have a fair bit of luggage (beer, mostly!) with us as we go to Paris, and then back to Brussels to fly out.

The difference is pure capitalism, the laws of supply and demand, what the market can bare.
Both trains will be identical. The price is dictated by how fast the tickets sell. The computer calculates the demand and sets the price appropriately, this is the same software as used by budget airlines to set prices. The earlier train presumably is more popular with people returning after business meetings or work. The prices also vary between different days of the week for the same reason.
Prices only ever go up nearer the date, they never go down.

Economy is the same as second class. 2+2 seating.
Premier = 1st class = 2+1 seating, with proportionately more legroom.

The luggage space is the same in 1st and second class. The difference is that there are fewer people per coach in 1st class, so more space per passenger.
Also first class passengers are business/work travellers, who have only been away for 1-2 days and have less luggage than tourists.