Question about Delay/Silence commands and gui correlation

[nalllen]

Got two questions that i hoped someone could help me with.

Is the command "delaycut -startdelay 100 -i myfile.ac3"
the same as using the Insert Silence option in the gui or is it like using the Delay option in the gui with Preserve Lenght unchecked?

if its Delay then what is the command for silence?

lastly what's the difference between between Delay with preserve length unchecked and inserting silence?