The Senate bill would give more small businesses access to the new exchanges quicker than the House bill. In the Senate bill, any business with 100 or fewer employees could use the new exchange. Starting in year four (2017), individual states could choose to allow larger businesses to also use the exchange.
Conversely, the House bill only allows businesses with 25 of fewer employees access to the new exchange in the first year. That is upped to 50 employees the second year, and 100 employees for year three. In year three, the new commissioner could choose to start allowing even larger employers to use the exchange.
The Senate bill would open up the exchange to more small businesses when it is first created. It would unfortunately delay the possibility of opening up the exchange to all employers by one extra year. It is important to remember that the House bill would start most reforms in 2013, while the Senate bill delays the start of the reforms until 2014, purely to make their bill look cheaper. So, in theory, there really is only one year (2015) when some small businesses (those with 50-100 employees) could not use the exchange under the House bill, but could under the Senate bill.
When/if the bills are merged in conference, I would like to see the Senate provision giving all businesses with 100 or fewer employees access to the exchange right away preserved. The three-year phase-in in the House bill seems an unnecessary delay in expanding access to the exchange and potentially the public option, which would only be available on the new exchange.
In the end, the practical effect may be very small. The CBO predicts that only a tiny fraction of eligible employers will take advantage of letting their employees select insurance on the exchange. Unless the exchange is improved, no one is really going to want to get insurance there. If you really want to increase the number of people using the exchange, you don't just need to increase potential access, you also need to give businesses and individuals a strong incentive to use it.
Read Part 1 Wavier For State Innovation and Part 2 Cantwell's Basic Health Program.