I assume you mean pitcher plants, not picture plants. On a very general level, you could consider them the same, as they are both in the plant family Sarraceniaceae (The Pitcher Plant Family). However, they are in different genuses: cobra lilies are in the monotypic genus Darlingtonia, pitcher plants are in Sarracenia. Their evolution is not entirely understoond, but it is likely they both evolved from the same, now-extinct plant species. Some mistakenly think the cobra lily and Sarracenia psittacina are closely related because of similar appearances, but the fangs of the cobra lily correspond to the hood in Sarracenia.
One thing i didn't think of, if you are talking about Nepenthes pitcher plants, they are unrelated to the N. American pitcher plants.
