Yes, that is exactly what you should tell them. 1  If two clauses are connected with a coordinating conjunction, it's a compound sentence. 2  If two clauses are connected with a subordinating conjunction, it's a complex sentence.
Trains were first- 1784, but cars weren't invented until 1890.
First public transport system without animal traction, first public line with no rope hauled sections for main journey, first twin track, first railway between 2 large towns, first timetabled trains, first railway stations, first train faster than a mail coach, first tunnels under streets, first proper modern railway which formed the template for all subsequent railways.