Free Sugar/Vtiger/VTE Comparison - Personal and Social tools

	VTECRM	VTIGER	SUGAR
Calendar module	yes	yes	yes
Shared agenda between users	yes	yes	no
Distinction between event and task on calendar	yes	yes	no
Meetings, Calls, Tasks separated modules	no	no	yes
Event/task archived in the related record	yes	yes	yes
Shortcut link from event/task to record	yes	no	no
Inviting users and contacts to an event/task	yes	only user	yes
Public/private visibility of event/task	yes	yes	no
Quick research between weeks-months-years	yes	no	yes
Email module	yes	yes	yes
IMAP supported	yes	yes	yes
Creating/linking a record starting from an email	yes	yes	yes limited
Sharing emails and comments with other users	yes	no	no
Distinction between single or multiple sending mode	yes	no	no
Email customized templates	yes	yes	yes

This area involves calendar and email.
Calendar: all three the software allow each user to have an internal calendar.
Shared calendar: Vtiger and VTE allow users to share their calendar according to the privileges. I add an event (specific day and time) or a task (sort of memo), they can be private or public. This is not possible in Sugar.
In all three the systems, events/tasks are related to a CRM record (for example the customer), providing a history of the activities. From the record I can add a new event/task which is automatically linked.
Only Sugar provides separated modules for Meetings, Calls and Tasks. Personally I find this feature a little dispersive.
On the contrary, speaking of functions, VTE proves to be smarter. I just have to click the “box” of the event to access the link to the related content, without opening the full form. I can move back and forth in weeks, months, years through a quick mini-calendar. I can invite other users and contacts (for example a customer) to an event. Some of these functions are available also in Sugar.
Let's see the email module. Very similar: it supports IMAP, I can do all the common actions I have to do on emails, I can save email templates, create/relate records starting from the email, and so on. The main difference is about sharing an email between VTE users, without forwarding and sharing comments about the emails too. This is a big plus. Another trick is the “multiple sending” mode which respects the privacy of each recipient (sort of advanced BCC).
All three the systems provide the creation of email templates.

	VTECRM	VTIGER	SUGAR
Chat between users	yes	no	no
Users' messages related to records and searchable	yes	no	no
Notes/comments on records	no	yes	yes
FAQ module	yes	yes	no
Sharing FAQ with customers via Customer Portal	yes	yes	no
Connection to customers' account on social network (es: Twitter)	no	no	no

Here, social means tool for sharing information between users, because there isn't any connection with social networks like Twitter or Facebook.
Chat between users: the VTE Talks module I have mentioned in the previous round is a fabulous tool for sharing messages and objects. I talk to my colleague about, for example, the customer's order, linking the record and saving the communication history so that tomorrow I could search something through keywords. The general Talks panel allows me to mark them as read/unread like emails.
In Vtiger and Sugar I add a comment within a record shared with my colleague but that's all.
FAQ: Vtiger and VTE have a Frequently Asked Questions module that I can share with users and customers (via Customer Portal).

Read all the comparison work about Sugar/Vtiger/VTE free edition 

The comparison work is based on

SUGAR 6.5 COMMUNITY
VTIGER FREE 6.3
VTECRM COMMUNITY 15.05
All three the versions are free and downloadable from their official sites.