Optical compressor vs. VCA based compressor

[thrillkillkult]

new to the world of audio and was just wondering...

what are the main differences between Optical compressors and VCA based compressors?

also, when would i use either of these compressors?

any info would be great. thanks!

 

[mixsit]

Plenty of overlaps here likely- VCA- faster, 'harder sound. But then there's these non-optical comps that also imulate optical and other styles.