Credibility relates to a witness’s sincerity, whether she is speaking the truth as she believes it to be.  
Reliability relates to the actual accuracy of her testimony.  In determining this, a court will consider a witness’s ability to accurately observe, recall and recount the events in issue.  A credible witness may give unreliable evidence.
R. v. Morrissey, 1995 CanLII 3498 (ON CA), [1995] O.J. No. 639 (Ont. C.A.) per Doherty J.A. at para 33; R. v. H.C., 2009 ONCA 56 (CanLII), [2009] O.J. No. 214 (Ont. C.A.) per Watt J.A. at para. 41; Paciocco and Stuesser, The Law of Evidence, 6th ed. (Toronto: Irwin Law, 2011), at pp. 32 – 33.
Accordingly, there is a distinction between a finding of credibility and proof beyond a reasonable doubt.  
R. v. J.J.R.D., 2006 CanLII 40088 (ON CA), [2006] O.J. No. 4749 (Ont. C.A.) per Doherty J.A. at para 47; R. v. J.W., [2014] O.J. No. 1979 (Ont. C.A.) per Benotto J.A. at para. 26.
 Finlayson J.A. stated in R. v. Stewart that:
I am not satisfied, however, that a positive finding of credibility on the part of the complainant is sufficient to support a conviction in a case of this nature where there is significant evidence which contradicts the complainant’s allegations.  We all know from our personal experiences as trial lawyers and judges that honest witnesses, whether they are adults or children, may convince themselves that inaccurate versions of a given event are correct and they can be very persuasive. The issue, however, is not the sincerity of the witness but the reliability of the witness’s testimony. Demeanour alone should not suffice to found a conviction where there are significant inconsistencies and conflicting evidence on the record.
R. v. Stewart, 1994 CanLII 7208 (ON CA), [1994] O.J. No. 811 (Ont.C.A.) per Finlayson J.A. at para. 19.
See R. v. Connolly, 2017 ONCJ 370 (CanLII).