Online retail behemoth Amazon launched its "Subscribe and Save" program in 2007, but traditional brick-and-mortar retailers are only recently jumping in to offer competing programs. There are also start-ups such as BirchBox and Dollar Shave Club that are making the subscription space even more competitive.
Read MoreWarby Parker co-founder takes on Gillette
Sam's Club, a business unit of Wal-Mart, began a pilot program for subscription service in February. Wal-Mart tested, but ended, a snack subscription program called Goodies.
Target recently expanded its pilot subscription service, from just 200 eligible items to about 1,500. The big box discount retailer also added a 5 percent discount and free shipping for all subscription orders. If shoppers pay with a Target REDcard, they can layer on the additional 5 percent savings.
Target initially launched the service in September 2013, with a focus on baby-care items. The retailer said the subscription service now accounts for more than 15 percent of online sales for eligible items.
Read MoreAMZN vs. GOOG: Who wins on same-day delivery?
Target does not provide total online sales numbers, but is expected to report its latest earnings on Wednesday. In its fourth-quarter conference call, Target said its online sales grew more than 20 percent, year over year, while total sales fell 3.8 percent. In the first quarter, analysts surveyed by Thomson Financial expect the discount retailer to earn 71 cents a share on revenue of $17.01 billion.
So which subscription program is better, Amazon or Target? CNBC did a test with identical products to compare the two. (And neither company was immediately available to comment on the results.)