Heap tables are found in memory that is used for high-speed storage temporarily. They do not allow BLOB or TEXT fields.
Heap tables do not support AUTO_INCREMENT.
Indexes should be NOT NULL.
The temporary tables are used to keep the transient data. Sometimes it is beneficial in cases to hold temporary data. The temporary table is deleted after the current client session terminates.
The heap tables are shared among clients, while temporary tables are not shared.
Heap tables are just another storage engine, while for temporary tables, you need a special privilege (create temporary table).