Question: Most forums cite minor differences in speed, backup, etc.
It's about time someone tell how the two differ when it comes to GUI data validation.
Do this 2 Database always depend on java(or other software), or do they have the ability to create a user interface the accepts only valid input. Things like: positive numbers only, age between 1 to 100 only, email must be correct. I would be scared if my software accepts 500 years old for age.

Answer: 
< T > refers to a generic type.
Generic types are introduced in Java to provide you with compile time, and this is important due to type erasure, type-safety.
It's especially useful in Collections because it frees you from manual casting.

It is a good idea to read more on generics, especially the documentation on the topic by Angelika Langer is very good: <http://www.angelikalanger.com/GenericsFAQ/JavaGenericsFAQ.html>
This is [parametric polymorphism](http://en.wikipedia.org/wiki/Type_polymorphism#Parametric_polymorphism), another important form of polymorphism other than subtyping.

In Java land, they call it [Generics](http://www.oracle.com/technetwork/java/javase/generics-tutorial-159168.pdf) (see also [Lesson: Generics](http://docs.oracle.com/javase/tutorial/extra/generics/index.html)).