Best Way to Upgrade from Norton Internet Security (NIS) to Norton Security

We currently have Norton Internet Security on our (ten) workstations.  The ten user license if about to expire.  Are there any advantages to using/upgrading to Norton Security vs. NIS?  Is the underlying engine different/better or is the primary difference updated definitions?

Assuming we go with Norton Security, should we remove the existing NIS software from the workstations first or just install Norton Security over NIS?  If NIS removal leads to a better experience, we're glad to do the extra work.

Thanks very much for your assistance with this.