<p>A few years ago I have worked on a green field project where we did Extreme Programming. I also see a lot of people mention the Scrum methodology.</p>

<p>Could someone tell me the main differences between Scrum and XP?</p>

Scrum is a software development methodology, XP is a programming practice. Both are "agile" techniques and are often used together.
Scrum outlines a process for identifying and cataloging work that needs to be done, prioritizing that work by communicating with the customer or customer representative, and implementing that work using iterative releases.
When my team first started experimenting with Scrum I found the
Implementing Scrum
website to be helpful.