Tradeoffs

There are tradeoffs associated with each type of PAC. 

Connected PACs can devote 100% of their funds to making contributions to candidates. But they can only solicit (and accept) contributions from individuals with a "connection" to the PAC (executives, employees, shareholders, members). But they are allowed to use funds from the connected organization to cover expenses such as legal fees, office space, and supplies- which would typically come from the PACs funds. 

Non-connected PACs may accept funds from anyone (who isn't otherwise prohibited from contributing to political committees). However, they must pay for all expenses (including legal fees, office space, and supplies) from PAC funds. This effectively means that contributions to non-connected PACs do not go 100% to candidate contributions; some funds are used for operational expenses. 

Super PACs (Independent Expenditure Only PACs) can accept unlimited contributions from individuals, corporations, and unions. But they may not contribute directly to political candidates; they may only fund Independent Expenditures.