Learn Hardcore Vietnamese: Phim này thú vị hơn phim hôm trước. - This movie is more interesting than the one the other day.

hơn is the Vietnamese comparative marker equivalent to “more … than.” It links the adjective thú vị (“interesting”) with the thing being compared (phim hôm trước). The basic pattern is:
A (adjective) + hơn + B (noun).

Why is there no separate word for than as in English comparatives?

In Vietnamese, hơn covers both “more” and “than.” You don’t need an extra particle. For added emphasis you can insert so với (e.g. hơn so với), but it’s optional.

Why doesn’t the sentence use a classifier like bộ before phim?

Everyday speech often drops bộ when referring to a movie. Phim này is perfectly natural. Using bộ phim này is more formal or explicit, but both are correct.

Could I instead say Bộ phim này thú vị hơn bộ phim hôm trước?

Yes. Adding bộ before each phim is grammatically fine. It just sounds a bit more formal; the meaning stays the same.

What does hôm trước mean, and how is it different from hôm qua?

hôm trước means “the day before” or “the previous time” (more general).
hôm qua specifically means “yesterday.”
Using hôm trước implies any earlier occasion, not only the immediate previous day.

Why is there no verb like là (“to be”) in Phim này thú vị hơn phim hôm trước?

Vietnamese often omits the copula là between a noun and an adjective. So phim này thú vị is understood as “this movie is interesting” without needing là.

Is it okay to drop hôm and just say phim trước?

Yes, phim trước can mean “the previous movie,” but without hôm, it may sound like you’re comparing sequels or installments. Including hôm clarifies you mean “the movie from earlier.”

How would I use the same structure to say “This book is more interesting than the previous one”?

Just replace phim with sách (or cuốn sách) and keep the pattern:
Cuốn sách này thú vị hơn cuốn sách hôm trước.