Suppose if I've a Lambda script to invoke EBS snapshots. Few days later, I'm invoking the snapshot of the same EBS volumes but via AWS CLI with different name and description. Would the new EBS snapshot be incremental by recognizing the EBS volumes or Would it be considered like a new snapshot? Kindly clarify.
Yes, it will be the same incremental snapshot.
However, if you copy the snapshot and encrypt it later on, new one will be created from scratch. From docs:
If you copy a snapshot and encrypt it to a new CMK, a complete (non-incremental) copy is always created, resulting in additional delay and storage costs.
Similarly, if you copy it to a new region:
If you copy a snapshot to a new Region, a complete (non-incremental) copy is always created, resulting in additional delay and storage costs.
More on copying snapshots and incremental support is described in Incremental snapshot copying.