The back-office remains the same for both V3 and V4, serving as a shared web portal for both versions.
Once V4 is activated, the following changes will take place:

[ 1 Phased Out V3 Screens ] [ 2 Partially Deprecated V3 Screens ] [ 3 New V4 Screens ]

Phased Out V3 Screens

V3 Screen	Replacement in V4	Release

V3 Screen	Replacement in V4	Release
Tickets list	V4 Tickets list	RIMV1
Support Ticket screen	V4 Support Ticket screen	RIMV1
Support Spectator screen	V4 Support Spectator screen	RIMV1
Settings > Assignment configuration	Still visible but ignored. Replaced by V4 Data Collection Rules.	RIMV1
Settings > Multilingual Settings > Emails & Notifications	Still visible but ignored. Replaced by V4 Communication Templates.	RIMV1
Campaigns list	V4 Campaigns list	RIMV1
Create/Edit/View Campaign	V4 Create/Edit/View Campaign	RIMV1
CSV Injection screen	Hidden → eventually replaced by V4 equivalent in RIMV2	RIMV2
Manual Injection screen	Hidden → eventually replaced by V4 equivalent later	RIMVx
Pending screen	Hidden → eventually replaced by V4 equivalent later	RIMVx