To answer your question we need to look at how clouds work. Generally speaking Allocation means that a resource is available for use while scheduling means that it is actually planned for use in the near future. Now if the resource can be actually used, is another issue and this is where online rescheduling occurs. In the cloud context the term resource can mean two different things as seen next. Moving to clouds we should be aware that there are two levels of allocation/scheduling: the platform level where virtual machines are allocated and user tasks are scheduled for execution on them; and the infrastructure level where physical machines are allocated and virtual machines are scheduled to run on them.

I think you should differentiate - when having anticipated or/and cyclic spikes of resource demand, you can schedule resource demand and plan (schedule) accordingly your cloud resources, allow for a change with your provider, etc.

"Allocation" means that you are allowed to use the resources, scheduling gives you the resources. You may be allowed to go in a lift, but the lift may still be full.

When a user request arrives at the cloud, resources are allocated to it initially. Afterwards, resources are scheduled for sub-tasks.

To answer your question we need to look at how clouds work. Generally speaking Allocation means that a resource is available for use while scheduling means that it is actually planned for use in the near future. Now if the resource can be actually used, is another issue and this is where online rescheduling occurs. In the cloud context the term resource can mean two different things as seen next. Moving to clouds we should be aware that there are two levels of allocation/scheduling: the platform level where virtual machines are allocated and user tasks are scheduled for execution on them; and the infrastructure level where physical machines are allocated and virtual machines are scheduled to run on them.

Resource management includes resource discovery, resource scheduling, resource allocation and resource monitoring. Resource discovery identifies .the suitable physical resources in which the virtual machines are to be created matching the user's request. Resource scheduling selects the best resource from the matched physical resources. It actually identifies the physical resource where the Virtual machines are to be created to provision the resources from cloud infrastructure. Resource allocation allocates the selected resource to the job or task of user's request. Actually, it means the job submission to the selected cloud resource. After the submission of the job, the resource is monitored.

Job scheduling selects the next job to be executed. After this job submission, the job is also monitored(Job monitoring) to track the status of the job.

Thanks all

Scheduling is about planing and, eventually, allocating

So cloud resource allocation is a potential subtask of cloud resource scheduling,

i.e. scheduling plans about which cloud resource should be used when

Cloud ressource allocation is to find waht ressource available free and use it ,

resource shudeling is how to plan the task where will be rxecuted

All great answers. Scheduling is the process of determining which resources to allocate for the execution of a task, and then ordering the execution of tasks. On the other hand, scheduling policy consists of a collection of rules to define resource allocation for the tasks submitted (a cloud scheduler needs to be aware of the available resources to allocate resources for carrying out a task).

Allocation is the provision of resources--CPUs, RAM, disk capacity, network bandwidth (even power and cooling) to support user(s) or shared set of applications (e.g., big data processing). Scheduling typically applies to running processes on a planned basis and it can also apply to scheduling of users based on SLAs.

Allocation is the assignation or reservation of resources at the time of request. Scheduling is a _request_ for allocation at a specific time or time period. The result of an implementable schedule request should result in the allocation of cloud resources (vCPUs, tier storage, etc.) so they are ready and available at the scheduled time.

now we know the difference in Theoretically 

we need  to know the difference practically in cloud computing where this Terminologies in cloudsim simulator ??

with my regards 

I think that

Resource allocation is VM provisioning (user or request to VM)

and

Resource provisioning is PM provisioning (VM to PM)

VM(virtaul machine).  PM(physical machine)

Resource allocation entails provisioning the required/available resources to tasks while scheduling determines what order these tasks arrive and leave the resources for the purpose of efficiency

Ayokunle Omotunde can I say - resource allocation is what to allocate and scheduling is when to allocate?

@Shaifali Malukani. Precisely

In addition to what they said colleagues

Resource allocation in cloud computing which is more general can include the following: