What's the difference between immigrant countries and non-immigrant countries?

Looking at immigrant countries and non-immigrant countries from the perspective of immigration history.

Germany is not an immigrant country, mainly because historically it was not imported by immigrants. However, Germany also has immigration laws, mainly for applicants who have worked, invested or reunited with their families in Germany for a long time.

On the contrary, the United States, Canada and Australia have always been countries with a large number of immigrants in history, and they are also countries with a large number of immigrants at present (especially Canada and Australia). Therefore, these countries have formulated detailed immigration laws and provided a large number of quotas every year to attract immigrants from all over the world.

There are many ways to immigrate to the United States, such as reunion immigration, investment immigration, and immigration after obtaining a work visa.