Their methods of interpreting information are diametrically opposed. Ni is abstract, metaphoric, free-form, and fuzzy with regards to how it makes connections, whereas Ti is more rigid and linear. Ni works from a top-down approach, presenting the information most relevant to the (meta-)perspective it is trying to convey; on the other hand, Ti builds from the bottom-up, presenting its perspective after all of the information. Tension can arise when Ti demands more strict, coherent thought processes than Ni can provide, creating a loop whereby the former shoots down all ideas conjured by the latter as logically invalid, often resulting in analysis paralysis because the vessel doesn't know what to do/how to respond to its environment. There are a few members on the board who can depict a healthy Ni-Ti loop; perhaps they will chime in eventually.