The terminology is murky any not completely clear-cut, but here's my take on it. Others are welcome to agree/disagree/modify as desired. I hesitate to give examples of programs in each type so as not to step on any toes.
Academic: Generally programs centered at university hospitals with high research output. These programs may (but not always) suffer from issues such as lower patient volumes or over-reaching specialty services that may reduce the number of procedures in the ED. The hope is that these traits allow for more teaching on shifts.
County: May be characterized by large patient volumes, more underserved populations, and (hopefully) greater resident autonomy. The places I consider "county" are typically more chaotic but allow for more procedures and greater resident responsibility, perhaps due to less attending oversight.
Community: This designation is the most difficult to label because some community programs are fiercely academic, others are as wild as the "county" programs but simply have a better patient mix. I would instead label such hospitals/programs as "Balanced". These are programs that have a very broad patient mix (if one hospital) or feature several hospitals that allow for a diverse residency experience. There is ideally balance between didactics and hands-on learning.
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The key is to identify the learning & training style that fits you and hopefully such a program will help you become a good doc.