The use cases for Milo and helmet radios are different, which results in several fundamental feature differences.
Helmet radios are typically integrated with full-face helmets, so both mic and speakers are protected, making the handling of wind and road noise less important than for Milo, which is worn attached on outer clothing, a handlebar or bag strap, or on an armband. Milo therefore incorporates its own wind reduction software.
The main controller for a helmet radio is usually mounted on the side of the helmet and uses combinations of what are often unintuitive and hard-to-remember combinations of multi-button presses. Instead, they tend to rely more heavily on mobile app integration. Milo is heavily geared towards hands-free and eyes-free use with very simple button interactions.
When in a group, one helmet radio typically acts as a leader with all others being followers. In contrast, all Milos in a group are equal participants in the group without any hierarchical configuration. Anyone in the group can add another Milo to the group.
Milo relies on audio notifications to keep everyone in the group informed about who's online and who is out of range.