MDA - aka "SALLY"

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MDA (3,4-methylenedioxyamphetamine), often called “Sally" is a psychoactive substance that was difficult to classify for much of its existence. Initially described as a unique psychedelic with an unusually powerful emotional component, MDA’s more precise classification as an entactogen didn’t occur until after the discovery of MDMA—a discovery that was partly inspired by MDA. While entactogenic drugs often possess some qualities of other drug classes, such as psychedelics or stimulants, they are specifically characterized by their tendency to produce feelings of closeness with others, relatedness, and emotional openness.
 
MDA vs. MDMA
MDA and MDMA are often compared to one another for a number of reasons: Both belong to the same drug classes, are generally used in the same settings, and have historically been encountered in the same forms. At face value, it may be easy to consider the two substances interchangeable, but MDMA and MDA are two distinct drugs, each with their own unique dosages, durations, and effects. A closer look reveals the more subtle differences that set each substance apart.
The most immediately apparent difference between the two lies in their names. MDA’s full chemical name is 3,4-methylenedioxyamphetamine, while MDMA’s is 3,4-methylenedioxymethamphetamine. Though their lengthy names differ only slightly, the four additional letters in MDMA’s name, “meth,” indicate that the MDMA molecule has one additional carbon atom and two additional hydrogen atoms compared to MDA.
This difference of only a few atoms, insignificant as it may seem, radically alters the way the two drugs interact with the brain. MDA, unlike MDMA, has the ability to act as a serotonin receptor agonist. This property, in which MDA can mimic serotonin and bind to its receptors, is similar to how many “classical” psychedelics, such as acid and shrooms, function in the brain.
The role of MDA as a serotonin receptor agonist may explain why many users describe MDA as “more psychedelic” than MDMA. While MDA is capable of producing visual effects, they are often different in character and less pronounced than those produced by other common psychedelics.
After consuming MDA at home with his wife, Reddit user /u/bob493 stated, “It was more ‘party’ than ‘love.’ MDA was by no means unpleasant; it was glorious. It just didn’t have that soul-baring problem resolution that MDMA has. If you’re looking to PARTY, MDA is definitely the way to go.”
Many others who have used both substances also describe MDA as being more stimulating, less emotional, and longer-lasting than MDMA. Given this comparison, MDA may be better suited for high-intensity environments, such as parties and music events, while MDMA may be more appropriate in calm, relaxed settings.