Why does Lawrence of Arabia (1962) feel much more modern than Bridge on the River Kwai (1957)?

I saw Bridge on the River Kwai for the first time last night, and loved it. But one thing that struck me is that despite being made only 5 years prior to Lawrence of Arabia, it feels a lot more old-fashioned.

But why is that? They're both excellent films, made by the same director, and they're both war films (or war-film adjacent, at least). But despite the similarities, with Lawrence I feel like I'm watching an early film from the modern era, but I didn't get that with Kwai at all. (Although I did appreciate the use of actual Japanese actors, and the lack of subtitles when they spoke to each other.)

Was it the acting style, the cinematography, or something else? What makes a film feel modern to you?