Yes, there are some very fundamental differences. Firstly, with a large team of lawyers and consultants, and a long list of large clients with large transactions/disputes, a prestigious law firm like Phuoc & Partners can advise on various complex legal fields with large workloads at the same time.
Secondly, with offices located in many places in Vietnam, prestigious law firms can easily do the clients work anywhere with a minimum travelling cost. Thirdly, the legal service fees of prestigious law firms are usually higher than those of solo practice lawyers, however this is due to (1) administrative costs of office operation (office rental, human resources, professional training, business development costs, etc.), and (2) in order to serve clients, a prestigious law firm must maintain a full complement of lawyers and support staff in many different legal fields at many locations, so their wage cost is high.
Therefore, depending on what type of legal work you require, your location and your budget, whether the transaction/dispute be complex, large or small, you will make a choice between a prestigious law firm or a solo practice lawyer.