When you're a new college grad, it's assumed that you know jack but are hopefully smart enough that you can learn it. Even if you've had some internships, it's understood that someone else was calling the shots, and you're just doing what you're told. The only real exception here is folks who've shown some true entrepreneurship or have already made significant open-source contributions.
Therefore, the questions that most companies ask new college grads are to assess potential - what you got out of your college courses, what initiative you've shown in your life so far, what your general level of curiosity, intelligence, etc, etc, etc is. Hence lots of puzzle-type questions and softballs to give you a chance to highlight the best stuff you've done in the first 20 or so years of your existence.
However, when you have 15 years of experience, you'd better know your shit in several areas related to your work experience. Expect to be grilled in the top few technologies you list on your CV. Also, at this point, you're expected to have shown good judgement and leadership at some point, so expect to be asked about that. And savvy companies know that in 15 years, you've likely royally screwed up on some occasion, so expect to be asked about that in order to demonstrate hat you're honest, humble, willing to learn from mistakes, and a whole slew of other things smart developers want to see in their experienced comrades.
In other words, review your work experience so far - what have you learned? How have you demonstrated your value? Where have you grown? Where are you still growing? Be prepared to talk about those things - and don't pass up the opportunity to do so.
Many prospective employers and future coworkers will be concerned that your knowledge is 15 years old, so be prepared to answer potentially condescending questions about how you've kept your skills up to date (and I sure hope you have).
(Nevermind that everything interesting in software was discovered 30 years ago - that won't impress anyone who's not already very aware of the fact, so it's probably not worth pointing out.)
Oh yeah, and expect to code. At the very least, expect to show some code you've written. This should be true (at clueful companies) for new grads as well, but is typically more true for experienced hires.
I've been a programmer all those years and haven't pursued much on managing other people, would that work against me ?
Regarding the managing thing - not necessarily, though most programmers with your years of experience have managed in some capacity before, you so may be asked why you have not. In my experience, though, a lot of experienced programmers looking for jobs seem to be in the opposite situation - they've been managing for a few years and now are looking to get back into programming.