What the differentiation between them?
Aggregate means you have one switch/router and which consist of several interfaces and you aim increase the bandwidth within them hence grouping into one or more logical aggregation.
Meanwhile you have also multiple switches which you wanted to stack them in order to have single logical switch. This is very useful in terms of managing purposes. But unfortunately, not every switch has this feature.
And the newest technology is VPC. This allows you to aggregate the interface beyond the limit even different switch and located in different site. This usually implemented for data center matter in order to have extended layer 2 capability.
Hope this helps.