From arrl.org:
Those who use Amazon for online purchases can automatically donate to ARRL by opting to use AmazonSmile and designating American Radio Relay League (ARRL) as their charity of choice.
The AmazonSmile Foundation donates 0.5% of the purchase price of eligible AmazonSmile items to whichever charity you choose. Product and Marketing Specialist Jackie Ferreira, KB1PWB, reports that the benefit of AmazonSmile to ARRL for 2018 was $8,676, up from $8,022 in 2017.
Family and friends can select ARRL as their charity of choice too. There is no difference between Amazon and AmazonSmile in terms of making purchases.