"Jaka jest między nimi różnica" would sound a lot more natural than "rozdział". Actually, I don't think 'rozdział' could suit this meaning at all.
"I carry" = (Ja) noszę - generally, regularly
"I am carrying" = (Ja) niosę - at this very moment.
In this sentence it should read in english : i am carrying a heavy television not i am carrying the heavy television.
Well, the television may have been mentioned already. Anyway, the default answer has "a".
More to the point is that 'set' is redundant, has no benefit, and is solely there as the teaching of English in Poland includes it under the belief that it is a more proper form. Consequently almost every hotel offering an English translation if its services in Poland uses 'TV set' and 'radio set'.