Advantages and disadvantages of using one big server

Hi, I’m currently using two VPS servers with Liquid Web, and I want to have one big server. One server has around 5000 visits during one month, while another has a much smaller number like 30-40 users. Both servers share the same spec. May I move both of them to one server, and also increase the resources? What are the advantages and disadvantages of using one big server in comparison to having two of them?