I am not expert in this, but I liked your discussion and decided to investigate the topic. I think that CFA soft dollar standards (PDF) may be helpful to understand it.
the difference is, Who receives the products and services that are in addition to execution, (see the Definitions below)
using CP adjusted example:
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you work for client a1 - thro your broker b1 - who provides you with some brokerage services.
– research reports, etc. These research reports should be used only for the benefit of client a1.
you have a client c1 - who directs that his broker b1 will do the relevant trades etc. for him. In this case the brokerage that you (IM) pay to the broker pays services under “Client directed brokerage arrangement” that are provided by the broker to the client c1 directly, and scheweser says ” do not use brokerage from client a1 to pay for products or services purchased under client c1 directed brokerage agreement”
here is the link:
http://www.cfapubs.org/doi/pdf/10.2469/ccb.v2004.n1.4005
definition from the standard:
Soft Dollar Arrangement refers to an arrangement
whereby the Investment Manager directs transactions
to a Broker, in exchange for which the Broker provides
Brokerage and Research Services to the Investment
Manager. Soft Dollar Arrangements include Proprietary
and Third-Party Research Arrangements but do
not include Client-Directed Brokerage Arrangements.
Soft Dollar Arrangements are sometimes referred to
herein as Investment Manager-Directed Brokerage
Arrangements, where applicable.
Brokerage and Research Services refers to services
and/or products provided by a Broker to an Investment
Manager through a Brokerage Arrangement.
Brokerage Arrangement refers to an arrangement
whereby a Broker provides services or products that
are in addition to execution. Brokerage Arrangements
include Investment Manager-Directed and
Client-Directed Brokerage Arrangements.
Client-Directed Brokerage Arrangement refers to
an arrangement whereby a Client directs that trades
for its account be executed through a specific Broker
in exchange for which the Client receives a benefit
in addition to execution services. Client-Directed
Brokerage Arrangements include rebates, commission
banking, and commission recapture programs
through which the Broker provides the Client with
cash or services or pays certain obligations of the
Client. A Client may also direct the use of limited
lists of brokers—not for the purpose of reducing
Brokerage costs but to effect various other goals (e.g.,
increased diversity by using minority-owned brokers)
or geographical concentration