Eligibility follows the duties and the credential, not the employer's title. Appendix 2 lists engineer and scientific technician or technologist as separate occupations with different qualification rules, and the case has to be built on the one the applicant actually satisfies.
Which document decides it
The document that decides this question is the listing itself read next to the applicant's diploma. Hypothetical example: a Lévis technologist holds a three-year college diploma in mechanical engineering technology and a U.S. shipfitting firm advertises the role as engineer.
The engineer listing expects a baccalaureate or a state or provincial licence; the Scientific Technician/Technologist listing instead requires theoretical knowledge in an enumerated scientific or engineering discipline, the ability to solve practical problems in that discipline or apply its principles to basic or applied research, and work in direct support of a professional in one of those disciplines. If the person will independently sign off designs, the engineer listing is the one being claimed and the diploma alone may not satisfy it. If the person will support a licensed engineer's work and meets all of the technologist conditions, that listing may fit and the letter should say so plainly.
Ask the employer to rewrite the description around what is true, then match it to one listing. A file that claims both invites the officer to conclude that neither has been established.