Nowhere close to the same for a lot of reasons.
1) Zen isn't Japanese, neither is Buddhism. "Zen" comes from "Ch'an," which is Chinese. So it's not as simple as "They took something of ours, but we took something of theirs, so it's even."
2) If someone "practices Zen," then they are Buddhist.
3) If they are doing Zen-style meditation without actually being Buddhist, then they are using a tool from another culture. We can argue about cultural appropriation, but that's just simple cultural diffusion - people in "the west" have a problem - they see a tool from "the east" and adapt it to their needs.
None of that is what happens with Christmas in Japan. Seriously, this is why we can't have real conversations about life in Japan. Cultural diffusion isn't some kind of tit-for-tat game. Poking your head in, tittering behind your hand, and saying, "Hurr, durr, but what about white people doing Zen? Gotcha!" isn't constructive.
It's a good question - what is Christmas in Japan? I've been arguing for some time that Christmas and Japanese New Year are basically the same, so the Japanese are adapting Christmas to be something that their culture needs - right now, the Japanese need a day for romance. Valentine's Day didn't work out, because the men monopolized it, and women turned it into a game of obligations with White Day.
Halloween has become the "sexy holiday" in America, and is becoming that in Japan as well - but there just aren't a lot of times or places in Japan where you can sit down and be openly romantic with someone. Christmas, to a degree, is starting to fill that role.
And I might be wrong about that, but I'm confident in saying this: Japan doesn't know what Christmas is for, and they are figuring it out. Give them time. For now, they are just going through the motions. That's sometimes how cultural diffusion works. Cultural diffusion takes decades - or centuries - how long have you been in Japan? Less than a century? Then relax, and wait. It'll work out eventually.