If "spotted" means "noticed":
* Observed
* Discerned
* Detected
* Recognized
* Perceived
* Identified
If "spotted" means "marked with spots":
* Speckled
* Mottle
* Dappled
* Freckled
* Pattered
If "saw" means "looked at":
* Gazed
* Beheld
* Viewed
* Glimpsed
Please provide more context so I can give you a more specific answer. For example, "I spotted a bird and saw it fly away" would be different from "I spotted a leopard with black spots and saw it hunt."