Switzerland is in the Single Market for Manufactured goods as it closely follows relevant EU rules, and is also in a Customs Union for Manufactured goods, thereby granting full access in this sector. But at a cost of having to pay substantial Fees and allow Free Movement.
Ukraine, on the other hand chooses to uni-laterally follow many EU rules on Manufactured goods, but is not in a Customs Union, but nevertheless has significantly reduced tariffs in this sector. Ukraine is not subject to Free Movement or substantial Fees.
Lets imagine one possible scenario where Ukraine (or a Labour-led post-Brexit UK for that matter) chose to 'add-on' a Customs Union for Manufactured goods so that it did not require 'Rules of origin' checks. That would mean Ukraine has close to full access for Manufactured goods, yet without the Free Movement or substantial Fees.
So what is the crucial difference between this hypothetical deal and Switzerland's current access for Manufactured Goods?