GRR measures retention without the offsetting effect of expansion. It captures only contraction and churn, so GRR ≤ 100% by definition. GRR is the cleanest read on whether the product is structurally sticky; NRR is the read on whether the business is structurally compounding.
World-class SaaS GRR is 90%+ at enterprise and 80%+ at SMB. GRR below 75% in B2B SaaS suggests fundamental product or fit problems that high expansion can mask in NRR but cannot fix.