The market share of e‐commerce grocery is swiftly rising, but online product listings may present different environmental sustainability and public health information. We analyzed product marketing content available on retailer websites and product images, comparing plant‐based (PBFs) and animal‐sourced foods (ASFs). Over sixteen thousand marketing and labeling content observations were gathered from seven leading U.S. e‐commerce grocery retailers for top‐selling ASFs and closely‐matched PBFs (N = 134; n = 68 PBFs, n = 66 ASFs), including sustainability, mandatory information, health, sourcing, and hedonic/emotional claims. PBFs averaged 47 total claims, ASFs 28. On‐web claims were substantially higher than on‐pack (PBFs 34 on‐web, 12 on‐pack; ASFs 19 and nine, respectively). On‐web information for the same products varied considerably across retailers, especially for sustainability and mandatory information. PBFs presented mostly sustainability claims on‐pack and health claims on‐web. ASFs led emotional claims and made almost no sustainability claims across settings. Across settings, mandatory information compliance was greater among PBFs whereas ASFs notably lacked disclosures for foods with major allergens. Online grocery lacks standardization—businesses should regard differences as opportunities for marketing sustainable foods.