As Kendoiwan purports there are similarities between STPs and NTJs, particularly ESTP/ENTJ and ISTP/INTJ. Contrary to what has been misstated the two thinking type SPs are very similar to the judging type NTs due to similar interaction styles and because Ni-Te and Ti-Se combinations whether reversed are identical to on-lookers per Linda V. Berens and Dario Nardi’s booklet, Understanding Yourself and Others: An Introduction to the Personality Type Code.
I think that ISTPs can confuse themselves as ESTPs and vice-versa, when both are using their auxiliary functions well. I think that ISTPs can also confuse itself with ENTJ when they revert to their tertiary function (Ni). Where the difference is, is that the ISTP will confuse a lot of their Se usage as being Te for no other reason as that they are using Ni. As an ISTP I have confused myself as being ESTP/ENTJ for extended periods.