Difference between Open-SQL DELETE and Internal table DELETE query

ABAP / By

ztt_db_table2 is the Database table name

ParameterOPEN-SQL – DELETEINTERNAL TABLE – DELETE
WHEREDELETE FROM ztt_db_table2 WHERE contact_id = 102DELETE lt_internal_table WHERE contact_id = 102.
STRUCTURE DELETE ztt_db_table2 FROM ls_structureDELETE TABLE lt_internal_table FROM ls_structure
INTERNAL TABLE DELETE ztt_db_table2 FROM TABLE lt_internal_table——-
INDEX——-DELETE lt_internal_table INDEX 2.
DELETE lt_internal_table FROM 2 to 3.