ProQuest and the Dept. of Education allow you to filter your search results by education level (higher education, elementary, secondary) and target audience. EBSCOhost lumps education level under "Subject" instead, and does not have an audience filter.
The Dept. of Education has other education-specific filters such as "Laws, Policies, and Programs," and "Assessments and Surveys." These filters allow you to limit your results to those that deal with your topic and specific laws (such as No Child Left Behind) or assessment strategies or tools (such as California Critical Thinking Disposition Inventory).
EBSCOhost and the Dept. of Education allow you to filter by full-text directly from the results page; in ProQuest, the full-text filter is an advanced search option.***
ProQuest and EBSCOhost have UI Link built directly into your search results. In the Dept. of Education interface, it is called Direct Link (and it is sometimes even fussier than UI Link).
ProQuest and EBSCOhost contain many other databases beyond ERIC, and so their search interfaces might be more familiar to you, and easier to use. You can easily add those other databases to your search to broaden your results. The Dept. of Education site is only ERIC.
***If you find an article that looks great but isn't full text, don't give up! Use UI Link or Inter-Library Loan to access the article. That's why limiting your search to full-text only can often be detrimental to your search!
Tree icon by kitzsingmaniiz for the Noun Project