What do you do when the tracks don’t match?

Apparently, the trains in France use different tracks than those used in Spain. That being the case, trains traveling between the two countries, which is many, must stop and adjust their wheel width. On either side of the border are huge train stations where trains come to rest while adjustments are made. Fascinating. Below is a Google maps image of the two stations whose tracks run along the Mediterranean coastline.

Immense train stations on either side of the French/Spanish border