"Deep" tickling versus "surface" tickling
To me, alternate phrasing would be "deep tickling versus lighter tickling on the surface of the skin"
For example, I really like deep tickling on my sides and front of my abdoment, squeezing deeply. The "speed" or frequency of the tickle also makes a difference for me. Two or three slow, deep squeezes in a row, and then a few moments of a break, versus sustained, unrelenting deep tickling, are different experiences.
However I also really like lighter, gentler, surface tickling with fingernails under my arms, my ribs, my back, and inner thighs.
Deep tickling while tied up is tickle torture for me, which I thoroughly enjoy.
Gentle, surface tickling for me is more akin to playful foreplay, which I also love.
Depends on the mood and who I am with, I suppose.