Kittl is a canvas. You place type, choose textures and build the thing, and the result reflects whatever skill you brought. Its strength is print on demand work specifically: lettering, badges, vintage treatments.
Recraft is a prompt with unusually good controls. You describe what you want, steer the style, and it produces images and, unusually for this category, vectors. That matters for print, where a vector scales to any garment size without going soft.
The important difference is not craft, it is licensing. Recraft states on its own pricing page that images generated on the free plan are owned by Recraft, are publicly visible in a community gallery, and are not licensed for commercial use. So the tier most people evaluate on is precisely the tier they cannot sell from. Kittl's free tier is limited by a one-off allowance of tokens rather than by what you may do with the output. That distinction decides more real cases than any comparison of results.