Both posit the usual chemical mechanisms. Evolution essentially hypothesizes that this is all that is required for speciation (which could very well be true even if intelligent design turned out to be the truth). While mutation and selection can be observed, the connection to speciation is only hypothesized. Intelligent design posits a designer (an extra degree of freedom) in addition to the usual chemistry. Neither position can prove that their positions are in fact how speciation has occurred in the past, so Bayes' theorem gets discarded and we are stuck with Occam's razor for discriminating between the two. In this case, the only difference between the two positions is the argument of whether or not a designer was responsible for speciation (and doesn't even address the issue of whether or not a designer is REQUIRED for speciation, which is a different question). In this scenario, Occam's razor would select the hypothesis of speciation being caused by mutation/selection (i.e. evolution), as it does not have the open variable of a designer in the mix. For the audience, "degrees of freedom" is essentially a count of how many unverified premises are utilized in the construction of the hypothesis. With the verification of the existence of a designer, both hypotheses would be on equal footing with respect to what is the most likely cause of a specific case of speciation.
That's what you based your Occam's Razor conclusion upon?
Most Darwinians claim that Evolution is dependent upon:
1. Appropriate environment,
2. Natural Selection, and
3. Random Mutations.
Most ID-er's claim that ID is dependent upon:
1. Appropriate environment and
2. Intelligent Designer.
3 degrees of freedom versus 2, yet you picked the loser and wrongly ascribed Occam's Razor as your reasoning.
That's not very scientific...