Case interviews are definitely easier. I passed the McKinsey case interviews with just a week of prep. You don’t even need to go to business school; in fact, the CS/Eng. people who interviewed with me overwhelmingly performed better than the business majors.
To pass a coding interview at a top tech company (comparable to McKinsey status), you have to first learn how to code well (6 months minimum), then learn DS&A (another month or two), then practice 100-200 problems on LeetCode (another 3-6 months).
A smart high school student could probably read Victor Cheng, practice a few (20-40) cases, and pass the interviews. The only thing missing are the extracurricular and leadership experiences, which are pretty easy to obtain if you really seek them (just be involved and social).