With the options provided, the answer to the phrase that trade union differed from the labor unions is that trade unions were organized or formed by skilled workers or workers employed in the building while labor unions are group of workers regarding if skilled or not.
Serfs, likewise might be farmers but might also be craftsmen. The difference between the two was that the peasant owned his own land, while the serf did not. The serf owed labor duties to his lord, whereas a peasant owed nothing or, more usually, owed some sort of rent.
