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.
A small carriage propelled by a steam turbine powered engine was apparently invented by Ferdinand Verbiest, a Belgian, in 1672 while in China. It is argued that this constitutes the first 'car' ever invented, but the design was only 65cm long, had no seats or pilot controls, and was intended as little more than a toy.