The following differences exist between five-blade and six-blade hvls fans:

Number of blades and aerodynamic efficiency: A six-blade fan has more blades, so it can provide greater air volume and stronger heat dissipation. 

The five-blade fan has relatively fewer blades, a larger blade area, and higher aerodynamic efficiency.

Noise: Due to the large number of blades, a six-blade fan produces relatively loud noise when rotating. The five-blade fan has a larger blade area and relatively less noise.

Applicable scenarios: Six-blade fans are suitable for application scenarios that require larger air volume and stronger heat dissipation effect, such as large industrial equipment, 

high temperature environments, etc. The five-blade fan is suitable for application scenarios with higher noise requirements and higher aerodynamic efficiency, such as offices, libraries, etc.

To sum up, there are differences between five-blade and six-blade hvls fans in terms of aerodynamic efficiency, noise, and applicable scenarios. Which fan to choose depends on the

specific application needs and scenarios.