What is the difference between Solo Trumpet/Cornet, compared to 1st Trumpet/Cornet?

I’ve been researching TBDBITL a lot recently, and its differences to British Brass Bands, and I realized both of them have a Solo Trumpet/Cornet and 1st Trumpet/Cornet. Could someone explain the difference? In the OSU School songs packet, both share the same sheet music, so I’m just curious what distinguishes the two.