给你个标准答案，可要记住了喔。
all_tab_cols显示所有列，当然也包含隐藏列。
all_tab_columns不显示隐藏列。来源于all_tab_cols;

all_tab_columns视图是如下定义的：
select OWNER, TABLE_NAME,
       COLUMN_NAME, DATA_TYPE, DATA_TYPE_MOD, DATA_TYPE_OWNER,
       DATA_LENGTH, DATA_PRECISION, DATA_SCALE, NULLABLE, COLUMN_ID,
       DEFAULT_LENGTH, DATA_DEFAULT, NUM_DISTINCT, LOW_VALUE, HIGH_VALUE,
       DENSITY, NUM_NULLS, NUM_BUCKETS, LAST_ANALYZED, SAMPLE_SIZE,
       CHARACTER_SET_NAME, CHAR_COL_DECL_LENGTH,
       GLOBAL_STATS, USER_STATS, AVG_COL_LEN, CHAR_LENGTH, CHAR_USED,
       V80_FMT_IMAGE, DATA_UPGRADED
  from ALL_TAB_COLS
 where HIDDEN_COLUMN = 'NO' ;