Sales Manager
This is for people who have full control of leads within their organisation. They can see all the leads within their org, and can assign to other sales people within the teams they manage.
Can create leads which must have a lead organisation they can access as a customer organisation. Leads do not need to be assigned.
Can create customer organisations and contacts within their team. Ie any org they create is created within one of their teams, and any contact they create must be connected to a org they can access.
IMPORTANT: It is the company that a lead is attached to which determines access, NOT the membership of the profile attached to a lead. Eg lets say a sales manager "Jim" has access to a company called "ACME Limiited", and there is a lead for a user "Bob" who is at "ACME Limited". You might expect Jim to be able to access that lead, but they will only have access if the lead is connected to "ACME Limited". This is because its reasonably common for people from one organisation to be the contact for a lead for some unrelated organisation.
Normally used "on own organisation"
Sales
A more limited role, intended to be a member of a sales team, but without priviledge to see or modify leads for other people in the same team.
Can create leads which are assigned to themself, and can see contacts and customer organisations for the leads they are assigned to.
Leads they create must be connected to an organisation.
Can create contacts and customer organisations, but only when connected to leads they are assigned to.
Can be used with Sales Team View or Take Lead to provide further permissions.
Normally used "on own organisation"
Sales Team Viewer
This is intended to be used with the Sales role when sales people need the ability to see contacts and customer orgs within their team.
This role just gives access to see the same leads, contacts and organisations as for sales manager, but is view only.
Normally used "on own organisation"
Take Lead
This is intended to be used with the Sales role when sales people need the ability to take un-assigned leads and assign to themself. Does not convey any other roles.
Normally used "on own organisation"
How to use these roles
Typical partnership management solution : your partners will have the Sales Manager role on their own organisation, which allows them to create leads and manage their contacts, but they cannot see leads, contacts or companies from other partners.
Internal sales teams: If your sales people are not to be trusted with each others data (ie they might steal leads from each other) then give the Sales team only to regular sales people. Give their managers the Sales Manager role. If your sales people are trusted with each other's data then also give the Sales Team Viewer role. If you have incoming sales leads and want your sales people to be able to take (ie self assign) any incoming lead give them the Take Lead role