Sync is based on industry standard formats like iCal and vCard that have in them relatively few fields compared to what is provided in MRSware. The standardization bodies that put together these formats are trying to provide a set of fields that are readily available across many types of devices with different capabilities. Sync creates copies of your information from MRSware into your phone; it also takes copies of what is already in your phone and puts them into MRSware. Users can control what goes down to the phone from MRSware, but are not able to control what goes up from the phone (everything in the phone goes to MRSware).
MRSweb is a mobile-optimized web app that allows users to login and access their MRSware data. As compared to Sync, there are many more fields available and functions that can be performed. The data that is accessed via MRSweb is coming directly from MRSware -- it is not synchronized or stored on the device, instead being live and the same that you see in MRSware Desktop at any given moment.
Following is a table showing a comparison and discussion of what each tool does and where it fits in your mobile access plans:
Contacts Basic information like names, phone numbers, emails, etc
Appointments Basic location, date, time, and notes
Tasks Only available in Outlook, limited fields
Journals, Not available via Sync
Contacts Full relational info, including Activity,
Categories, Additional, Relationships, etc
Appointments Full Attendees, Categories, Labels, Types, etc
Tasks Available on all devices. Ability to assign tasks
Journals, Full access is provided.
On the other hand, MRSweb is designed to work consistently (the same) across many different device types. Since it is consistent we can do training and support once and that information applies equally well whether a user has a tablet or a phone, iOS or Android. However, also because it is the same across devices it is unable to take advantage of any special features one particular device has that another may not... Perhaps there is a particular style of navigation that a device uses or special settings area that it provides that adds value but would not be available to a MRSweb-type application.
In summary, Sync copies data to your device's native apps; MRSweb provides fuller access to MRSware features on all devices.