“TYPE STANDARD TABLE OF “refers to the standard table. It refers to a normal internal table which can be accessed via table index or by key in case if you have a key defined over a table while sorting.
“TYPE HASHED TABLE OF” refers to the generic hashed internal table. The table is created and data is stored using the hashing algorithm. The main advantage of the hashing algorithm is that accessing any part of the table is independent of the size of the table and hence an increase in the size of the table does not result in any delay inaccessibility of data. In case if you need to store large dataset and which is frequently accessed then prefer a hashed table.
“TYPE TABLE OF” refers to the generic definition of the table which can be used to refer to any type of table. But with the current Object-oriented paradigm, you need to specify at least standard or hashed in addition to type.