Direct answer
394/SR936SW and 380/SR936W both measure 9.5 × 3.6 mm and use silver-oxide chemistry. The maker numbers preserve the SW low-drain versus W higher-drain distinction.
Both are 9.5 mm in diameter; heights are 3.6 mm and 3.6 mm. Both are 9.5 × 3.6 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.