An aspect is a class containing one or more advice methods, which must have the signature
public Object <any-name>(Invocation inv) throws Throwable
The invocation argument must be of type org.jboss.aop.joinpoint.Invocation, or one of its subclasses.
An interceptor is a special type of aspect, and implements the org.jboss.aop.advice.Interceptor interface, which effectively forces you to create an aspect with one advice method.
But dynamic aop is possible with aspects ? Or aspects would have to implement Interceptor interface for this purpose?
In 1.5.x, dynamic AOP is most easily possible with interceptors.
In 2.0 it will be possible with everything. However, having said that you might be able to do it with 1.5.x as well. Take a look at org.jboss.aop.advice.PerVmAdvice, it is used to generate interceptor classes from aspects (in 1.5.x interceptors are used internally)