What is the difference between applying for a visa yourself and applying through an agency?

The difference between applying for a visa yourself and applying through an agency is mainly in terms of cost and time. The agency is faster and more expensive, while applying by yourself is slower, and some countries do not accept individual applications. An agency can apply for a visa for you only if you agree to let them act as an agent for you. Then they can use your materials to help you apply for a visa. Of course, you can also apply for it yourself. The key is to see what region the visa is for.

At present, individual tourist visas are basically open in Southeast Asia, and some places require group visas.

Individual travel visas are not available in Europe and the United States, but you can apply for personal travel with a business visa.

Others, such as study abroad and work visas, etc. may go through an agency. They will know all the materials and procedures better. Going through an agency will save you a lot of detours, but it will definitely cost a certain amount of money.