I would go with the HR definitions, but put the different departments you worked for in parentheses near each job title. For example: Development Engineer (Engineering Analyst)/Development Engineer (Business Development Analyst). I have had different jobs with the same title before and this is how differentiated. If there was a promotion or an increase in responsibility make sure to note that in the 1st bullet point of the more recent job (i.e. Promoted to development engineer in business dev dept to research and manage new supplier relationships).
Hope this helps.
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