Sparkfun offers free shipping on orders over $75, whereas Adafruit offers free shipping on orders over $200.
The Adafruit website is definitely more attractive. It is also somewhat better organized. Sparkfun is not as bad as it used to be, I have to give them that. The best approach on either site is still to do searches for things you want.
The really BIG thing that separates Adafruit from Sparkfun is that when they sell you a breakout board, they include the breakaway header you are almost sure to need. That is enough to win my business. But read about how they do really well on shipping time also. I thought that shipping from Colorado to Arizona would beat shipping from New York to Arizona -- but it actually takes twice as long.
Here is the tale of a recent order from Sparkfun. I placed my order at 2:00 PM on a Monday (July, 27, 2020). On Wednesday (July 29, 2020) at 2:40 PM I get an email notice that my order has shipped. I was already looking for the package in the mail, why over a 48 hour delay in shipping it. It is now Monday (August 3, 2020) and the package has not yet arrived. It is being shipped "FedEx Smart Post" (whatever that is). FedEx tracking indicates I will have it by the end of the day. That doesn't happen (it arrives the next day, 8 days after my order). I paid $7.09 for the postage.
At 8 days, a person could start thinking of just ordering direct from China (i.e. AliExpress ). When you can find what you want, you can save a lot of money and the wait varies, but is often just 2 weeks.
As a contrast, I ordered some nylon strap on Thursday (four days after I placed the Sparkfun order). It shipped from Durham, NC. It was in the mailbox along with my Sparkfun package. I paid $8.93 shipping for this item, and the package indicates it shipped USPS first class. I am eager to order something from Adafruit just to see how fast they ship.
One reason I chose Sparkfun rather than Adafruit was that I expected quicker shipping given that I am in Tucson, Arizona and Sparkfun is in Longmont, Colorado. I'll also notice that I ordered another item (a knife) from a seller in Oklahoma on Sunday -- it shipped on Monday and was in my hands by Wednesday via USPS express postage.
While I am ruminating about this order, I'll mention another oddity. I added a small item to the above order (a GPS antenna). The total added up to a lot more than I expected, so I took a closer look. Apparently that $4.00 item was getting shipped out of some kind of fulfilment center in Texas and postage for it was an additional $14.00. Needless to say I removed this item from my order -- but Caveat Emptor! Let the buyer beware when ordering from this outfit.
I got a message the next day, Wednesday August 5, but at 4:30 PM (7:30PM in New York) that a package will be shipped to me via USPS. On Saturday, August 8, 2020 the package is in my mailbox.
So 3.5 calendar days for Adafruit, and 8 days for Sparkfun. My choice is clear from now on, that is for sure. I get the package in half the time and save a few dollars on shipping. No sneaky fulfilment center in Texas either.
ADA Fruit and Sparkfun complement each other. ADA Fruit gets a big thumbs up for a superior website. Sparkfun has a lot more small items.
Sparkfun has lots of cool and interesting stuff, if you can find it on their website, which is sort of like an easter egg hunt. They do (or did) have a lot more components and small parts than ADA Fruit.
Tom's Computer Info / tom@mmto.org