Time Warner Inc. broke out financial results for HBO for the first time on Wednesday, showing that the premium cable channel is generating far bigger profits than emerging rival Netflix Inc. but HBO's revenue is growing at a much slower pace.

HBO generated $1.8 billion in operating profit in 2013, as revenue grew 4% to $4.9 billion, about 27% of Time Warner's total, the entertainment company disclosed as it announced fourth-quarter earnings results. HBO and sister channel Cinemax together added two million domestic subscribers in the year, ending with 43 million U.S. subscribers. Time Warner said HBO accounts for about two-thirds of that total.

Those results stand in contrast to streaming-video provider Netflix, which is positioning itself as a competitor to HBO, finishing 2013 with 31.7 million paid U.S. subscribers, a little ahead of HBO.

Netflix's revenue rose 21% in 2013 to $4.37 billion—not far behind HBO—but it generated only $228 million in operating income, as content expenses weighed down profit.

The two companies don't compete head-to-head—HBO is distributed as an add-on to cable TV packages, while Netflix is an online outlet that bills customers directly. But Netflix's rise as a subscription-TV service with edgy programming, including original shows, has drawn inevitable comparisons to HBO, and top executives from both Time Warner and Netflix have taken digs at each other in the past. TV industry watchers have been waiting to see if consumers will drop traditional pay-TV service, including premium cable channels, as they sign up for Netflix.