create table "TEST" ("Col1" bigint);

select table_schema, table_name from information_schema.tables where not table_schema='pg_catalog' and not table_schema='information_schema';

TEST = test       <-- non case sensitive
   "Test" <> Test    <-- first is precise, second one is turned to lower case
   "Test" = "Test"   <-- will work
   "test" = TEST     <-- should work; but you are just lucky.

select
   quote_ident(table_schema) as table_schema,
   quote_ident(table_name) as table_name
...

 table_schema |    table_name
--------------+------------------
 ...
 public       | good_name
 public       | "table"
 public       | some_table
 public       | "something else"
 public       | "Tom's work"
 public       | "TEST"
 ...