Here are charts which succinctly describe how immigrant workers form an hourglass: greater variance in education and in compensation.
The first chart shows the distribution of education status, comparing immigrants with native-born workers. Immigrant educational achievement concentrates at the extremes. The very high less than HS share among immigrants are primarily Hispanic. Recent inflows from Latin America have been more formally educated.
The second chart compares average wages by education status. Immigrants earn less except among college-educated where they are paid more.
Source: BLS for 2018