Agile vs Spiral, which one is better and why?

Which Software development methodology is better out of Spiral and Agile and why?

It's not that one is better. They are different and make sense on different projects. According to wikipedia, the spiral model is best for large expensive complicated projects. Spiral is like little waterfalls. If the customer need to specify things in advance, it is better than true waterfall.

I'm not convinced that there is any real difference between them. It is often a distinction without a difference.

To answer your question

Which Software development methodology is better out of Spiral and Agile and why?

The sweet spots of a process framework depends on the context of a project.
Without context no sensible comparison can be made.

According to wikipedia, the spiral model is best for large expensive complicated projects. Spiral is like little waterfalls. If the customer need to specify things in advance, it is better than true waterfall.

The reason for this is that in Agile model you have short sprints, with concentration on working software incorporating frequent requirement changes developed by a self disciplined/proactive team. So it's iterative and incremental approach suits well for smaller sized but highly dynamic projects.
Spiral model on the other hand is sort of repetitive waterfall model. Where each cycle focuses on working software delivered using proper processes and documentation. There is slightly more micromanagement involved and requirement changes are not incorporated at any stage of the iteration.