Fluorescence emission difference (FED) microscopy, as an emerging super-resolution imaging modality, uses double-exposure and subtraction between double-exposed fluorescence images to achieve high spatial resolution beyond the diffraction limit. Here we report on a new FED imaging approach with a single-exposure scheme based on dynamic cylindrical-vector fields, where the fluorescence excitation beam can be switched between radial and azimuthal polarization states at a designated high radio frequency. Lateral spatial resolution of ${\sim} \lambda/4$ is achieved. Being able to integrate with lock-in amplifier detection, the proposed method will find promising applications for high-speed fluorescence imaging with improved signal-to-noise ratio.