First of all, the resolution of SPM is extremely high. It can easily "see" atoms, which is difficult for a general microscope or even an electron microscope to achieve.
Secondly, SPM obtains real-time and real high-resolution images of the sample surface. Different from some analytical instruments, the surface structure of samples is estimated indirectly or by calculation. In other words, SPM really saw atoms.
Thirdly, the use environment of SPM is relaxed. Instruments such as electron microscope have strict requirements on working environment, and samples must be placed in high vacuum before testing. SPM can not only work in vacuum, but also be used in atmosphere, low temperature, normal temperature, high temperature and even solution. Therefore, SPM is suitable for scientific experiments in various working environments.