Agile Definition from wikipedia is as follows:-
Agile software development is a group of software development methodologies based on iterative and incremental development, where requirements and solutions evolve through collaboration between self-organizing, cross-functional teams.
Agile is like bucket which contains many different methodologies like SCRUM, Kanban, Lean...etc
SCRUM is one of agile development methodology for Iterative and incremental development.
IMHO, there is some learning curve while shifting from waterfall( or any other non-agile methodolody) to SCRUM. so please make sure you keep some time for the same.
I hope this helps.