The meanings are different. In the first one, the dealer helps. In the second, the policy helps. Can you confirm what "it" is? A dealer is a person so I can't imagine what "it" is. Should the "which" clause in the second sentence be non-defining? If so, add a comma to be clear.

The second sentence should be written in one of two ways, depending on the meaning you wish to convey: 1. These include a one-brand policy, which helps the dealer to create a holistic view of the brand presented by the dealer. 2. These include a one-brand policy, which helps the dealer to create a holistic view of the brand being promoted/used. I personally prefer to use a 'which' construction, rather than a 'so that' construction, but the former is not necessarily better English; it just reads more smoothly. So either sentence would constitute good English, but you do need to be clear whether the brand is being presented in the policy or promoted by the dealer. That is not clear from either of the sentences.