• Lift and Shift: Here we move the On Premise Application to a Virtual Machine on the Cloud . There is no change made whatsoever to the application. This method does not take advantage of advanced Cloud capabilities like Cloud Elasticity by making use of Platform as a Service and other new Technologies. But it is relatively easy to move Apps . In some cases , it’s a no brainer to use this method. For example , if your On Premise Data Center cost is substantially large as compared to simply moving to Cloud, then you should just go ahead with Lift and Shift. Another area where Lift and Shift is great is for Cloud Disaster Recovery which works out to be far more cost effective as compared to On Premise Disaster Recovery. The third area could be where it’s a ready to use application . So you have no access to the code as the Software Vendor controls the same. So the only option is to Lift and Shift.
• Lift and Shift and use Platform as a Service: In this model, one does not change the Software code. Instead one uses Cloud features. For example, if your application uses SQL Server, then you could use SQL Service offered via Platform Service by Azure. In this case SQL Server management will be done by Microsoft. Similarly you can identify various Platform Services that can be used.
• Changing the application code: This can only be done by the Software Vendor. Here the various parts of the code are changed to take advantage of the Cloud Technologies.

TechGyan can help you mainly with

1) Lift and Shift 
2) Lift and Shift along with using Platform as a Service.