What is the difference between application being refused or cancelled as incomplete.
I believe that an application is cancelled when it did not go through all the processes (checks and decisions outcomes) and mostly is rejected as incomplete due to some missing required documents. This happens mostly at the initial stage of your application. when that is the case, no further checks or processing are done and the application is cancelled and all the fees are refunded to you. It is as if they trying to tell that the application did not go through. It does not necessarily mean that there is something wrong in your application, but that it does not meat the minimum requirement to deserve being analysed. You are allowed to apply again immediately if you can fix the missing documents.
On the other hand, when your application has passed the completeness phase and is being processed ( examined) , if they find something that they do not like, by that I mean something like misrepresentation, security threat, or that you do not meet the eligibility criteria for what you are applying for, then they refuse your application. Since it was already being processed, your application fees will not be refunded. However, if you paid the Right of Permanent Residence Fee (RPRF) in advance, that fee only will be refunded.
For Misrepresentation, you can be banned to apply for 5 years. I don't think you can reapply if you are considered a security threat or have a criminal record. Well, you can re-apply but will be rejected again unless you fix the security or criminality concerns. As for eligibility, wait until you meet the criteria to reapply.
I hope I have answered your question to the best of my knowledge.