Hi there. Assuming you have a strong CV and just need someone to get you through the door, I’d say it’s not really about whether that person is internal or external, it depends on whether the referral has a good relationship with the recruiter. I know ex consultants who became headhunter later and helped consulting firms with recruitment. Their reference is in no way any weaker than an internal referral.
However, if we’re comparing apple to apple, say both internal and external recruiters don’t have a personal relationship with the recruiter and they’re just referring you through the official reference system, then yes, internal referral would be stronger in this case.
Hope this helps!