It’s pretty much that. Articles have a headline, then a subheadline (the deck or dek), which is usually used to expound upon the headline.

Back in the days of print the headline, subhed, and body all had to fit and look nice so there were limits to how many characters you could use with a headline and subhed and make everything fit and stand out at different sizes, so headlines wound up being written in a distinct style.

And now Google and Apple News and all the other have imposed limits on characters so it all remains. Everyone knows China can’t literally talk but everyone knows what “China, US to discuss” means, and if they don’t they can RTFA

AP style recommends <100 characters, hence stuff like this and the ubiquitous comma used in lieu of the word ‘and’, among other things.

But the ideal headline has even less characters than that due to search engines. 100 characters are an awful lot in that regard, so <60-70 becomes even better

Edit: didn’t take long for me to find an example for you. This is what is considered a ‘bad headline’: