Dual Mode means that the walkie-talkie supports dual working mode. for example, the Ailunce HD1 supports not only analog (Analog) but also digital (DMR) two working modes.
Dual-Band means that the walkie-talkie supports dual frequency bands. If only the UHF band is supported, then it is a single band radio, such as RT29; if it supports both UHF & VHF bands, then it is dual-band, such as HD1.
Dual Standby means that the walkie-talkie supports dual-channel standby. This function is common in dual-band radios, such as the HD1 mentioned above; but single-band radios can also implement dual-standby functions. The dual-standby function is of great significance for hobbyists who want to listen to two channels and commercial conductors who need to know two channels from different departments.
Dual display means that the walkie-talkie can display two channels at the same time. As shown in the figure below, RT73 supports dual display and single display radios.