Virtualization solves the problem of separating OS from hardware through hypervisor and multiple OS on a single physical server. whereas cloud computing solves the problem of separating software from OS and from hardware.
Management console, e.g. VMware vSphere, manages hypervisors. For example moves VM between physical servers, creating VMs, allocate resources and so on. There are 2 types of allocation: dynamic allocation and static allocation. In dynamic allocation, You could give more resources to VMs than the physical server can handle and the hypervisor will automatically arrange and share the resources. In static allocation, the resource will be allocated even if it is not used.