Hey,
I had a similar question and the answer I received was that the maven plugin results are more accurate.
However consider this, lets suppose you have an application that is built from multiple components and finally deployed in one host.
Approach 1(Jenkins Build) :- Scan the final deployed host via jenkins plugin, give it the directory of the jars , typically something like WEB-INF/lib/
All the jars are usually available in one place or just few other folders which you need to specify.
Finally, You will get one report.
Approach 2(Maven Approach):- Need to run maven dependency scan for each component , get its report.
So now you have 'n' reports for each component, which you need to analyse one by one.
I have completed both the approaches , and i believe finding and triaging issue while at maven build ensures shifting security left.
Thanks
Anvesh