I think it may mean air suction as opposed to mechanical, I am hazarding a guess as I have not used one, being a male it would be a bit silly to try ha.
If you click the top right of the page and enter Clitoral suction you may be able to find the topic you had read before.
Can you give an example of one of the toys you’re talking about that is confusing you? Maybe someone who owns it can help explain. I’m not sure what thread you’re talking about I’m afraid so can’t link to it.
Generally speaking though, the suction toys use what Womanizer describe as Pleasure Air Technology (but they all work in the same way). The end surrounds in a vacuum but doesn’t touch your clit and the toys create changes in air pressure that pulsate. Essentially they’re sonic vibrators and feel incredible.