In answering your question as it's written: I don't think you're really "missing" something. Different banks offer different rates. Online banks, or eBanking solutions, such as CapitalOne, Ally, Barclays, etc., typically offer higher interest rates on basic savings accounts.
There are differences between Money Market accounts and Standard Savings accounts, but primarily it comes down to how you can access your cash. This may vary based on bank, but Ally has a decent blurb about it:
Regular savings accounts are easy to open and, when you choose an
online bank like Ally Bank, you tend to get interest rates that are
more competitive than brick-and-mortar counterparts, according to
Bankrate.com. Additionally, as a member of the FDIC, Ally Bank gives
you peace of mind knowing that the money in your Ally Bank Online
Savings Account is insured to the maximum allowed by the law.
Money market accounts are easy to open, too. And again, online banks may
offer better rates than traditional banks. Generally, you have a bit
more flexibility of access with a money market account than you do
with a savings account. You can access funds in your Ally Bank Money
Market Account through electronic fund transfers, checks, debit cards
and ATM withdrawals. With savings accounts, your access is limited to
electronic funds transfers or telephone withdrawals (and in-person
withdrawals at traditional banks). Both types of accounts are subject
to federal transaction limits.
Here's a bit more information about a Money Market Account and why the rate might be a little bit higher (from thesimpledollar.com):
A money market deposit account is a bit different. The restrictions on
what a bank can do with that money are somewhat looser – they can
often invest that money in things such as treasury notes, certificates
of deposit, municipal bonds, and so on in addition to the tight
restrictions of a normal savings accounts. In other words, the bank
can take your money and invest it in other investments that are very
Now outside of your question, if you have $100K that you want to earn interest on, I'd suggest looking at options with higher rates of return rather than a basic savings account which will top out around 1% or so. What you do with that money is dependent on how quickly you need access to it, and there are a lot of Q&A's on this site that cover suggestions.