Nepenthes form lower pitchers when they are young or offshoots from the base of the plants.
Lower pitchers are always have their opening (mouth) on the same side as the tendril, and the tendril hangs straight down. Most lower pitchers are more colorful than upper pitchers and have "wings".
Nepenthes upper pitchers form on mature sections of the plant, that are of flowering age.
Nepenthes upper pitchers have their "wings" reduced to ribs and have their opening on the opposite side from the tendril, and the tendril often has a curl and/or will grasp objects to help the plant climb.
Upper pitchers are often less colorful and can be smaller than the lower pitchers.
To keep a plant with only lower pitchers, cut the tops and keep the plant short and bushy. For a plant with upper pitchers, have patience, let it grow, and do not cut the top off.
There are species that differ, but these are the general differences in upper and lower Nepenthes pitchers.
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