What is the same
Both are about 13 × 25 mm, 6-volt photographic stack cells used in many late-1970s / early-1980s SLRs. Retail packs may also say A544 or 544 — always read the chemistry printed on the pack.
What is different
4LR44 is alkaline. PX28 / 4SR44 is silver oxide. PX28L is lithium in the same outer size. Discharge curve and meter behaviour can differ even when the cell fits.
Canon AE-1 / AE-1 Program documentation centres on this 6V form factor. Prefer the chemistry named for your body, or the modern substitute your evidence source recommends — do not treat every label as identical.
Not a PX625
PX625 / PX13 / MR9 are 1.35V mercury-era button cells for other cameras and meters. They are a different problem. See the PX625 hub when your meter was designed for 1.35V.