Hi Vimee,
if I'm not wrong, the difference between role & designation can be curved out like this:
while Recruitment Executive is a designation, the roles played under this are CV Sourcer, Telecalling, Candidates Screening, Interviewing, Document & Background Verifying, etc.
While for an employee in a company, the designation On-paper is 1 but roles to be played under it may be multiples.
Every role can be a designation in itself, but no vice-versa.
Hope this is enough to understand the difference between roles & designations.