A template is a master copy of a virtual machine that can be used to create many clones.
When you clone a virtual machine, you create a copy of the entire virtual machine,
including its settings, any configured virtual devices, installed software,
and other contents of the virtual machine's disks.

A template is a master copy of a virtual machine that can be used to create and provision virtual machines.
It contains all the software and configuration settings that would make the VM work when deployed

Templates cannot be powered on or edited, and are more difficult to alter than ordinary virtual machine. A
template offers a more secure way of preserving a virtual machine configuration that you want to deploy many
times.
where as Clone VM can be power on

You can convert the template back to Virtual Machine to update the base template with the latest released patches
and updates and to install or upgrade any software and again convert back to template to be used for future
deployment of Virtual Machines with the latest patches.
whereas You cannot convert back the cloned Virtual Machine

Convert virtual Machine to template cannot be performed, when Virtual machine is powered on.
Only Clone to Template can be performed when the Virtual Machine is powered on
whereas A Clone of a Virtual Machine can be created when the Virtual Machine is powered on

Templates are best suited for production environments where you want the mass deployment of Virtual Machines
along with the installed OS, basic software, and configured settings such as the security policy of your organization,
as a base VM. Once a template is deployed, you can install software depending on the role of
the server for example IIS or Database
where as VM clones are best suited in test and development environments where you want to create, test and work;
with exact copies of production servers without disturbing production servers by creating a clone of the production
virtual machine.

A snapshot preserves the state and data of a virtual machine at a specific point in time.
The state includes the virtual machine’s power state (for example, powered-on, powered-off, suspended).
The data includes all of the files that make up the virtual machine.
This includes disks, memory, and other devices, such as virtual network interface cards.