There is a noticeable difference in weight (210 g (Inclusive of Battery and Cable) vs 270 g), which may affect comfort during extended use. Impedance levels vary (300 ohms (when noise cancelling function is used) vs 50 Ohms), which can affect compatibility and audio output when used with different devices. The frequency response differs (10 - 25,000Hz vs 15 Hz - 28,000Hz), which can influence how well the headphones reproduce lows, mids, and highs. Audio Technica ATH-ANC7b and Sennheiser HD 558 are well-known options in the wireless headphone segment, offering a balance of audio quality, battery performance, and smart features. Audio Technica ATH-ANC7b and Sennheiser HD 558 offer different noise cancellation capabilities (Yes (Reduces Noise up to 20 dB) vs NA), which can impact how effectively they block external noise. Both headphones offer solid battery performance, making them suitable for long listening sessions and travel. The driver size differs between the two (40 mm vs NA), which can influence sound depth, bass response, and overall audio clarity. Both models support modern Bluetooth connectivity, ensuring stable wireless performance with compatible devices. In general, both options are suitable for everyday use including music, calls, travel, and work-from-home scenarios.

Verdict: Both models are competitive, and your decision should be based on your usage needs and preferred features.