One possible explanation is simply that the lifestyle of the Native Americans did not require the advancements that the Europeans discovered. The saying, "Necessity is the mother of invention" has become a cliche for a reason; if the way something is being done is working for those completing the task, they have no incentive for seeking another level of technology for the task. Or, if someone does discover an alternative, others may not be particularly interested in changing, if there is not a significant (and obvious) benefit.
The level of interaction was different, so even those improvements in techology that might provide that large benefit were not easily shared and spread, so that the overall technology level might be viewed as inferior. (Consider, though, the Mayas and Incas, and their advanced medical and architectural/structural technology.)