Direct answer
362/SR721SW and 361/SR721W share the same 7.9 × 2.1 mm silver-oxide envelope. The retained distinction is the SW low-drain versus W higher-drain designation.
Both are 7.9 mm in diameter; heights are 2.1 mm and 2.1 mm. Both are 7.9 × 2.1 mm silver oxide / zinc cells at 1.55 V nominal, but their drain designations differ (SW: low-drain profile versus W: higher-drain profile). Preserve the device-specified class.
Do not infer acceptability from fit alone. The device maker’s complete code and current instructions remain authoritative.