Hello,
For Informal Malay,Usually "haribulan(hb)" and "tarikh" are same meaning.
For example If we want to ask someone about the date:-
Hari ini berapa haribulan? Or Berapa tarikh hari ini?
The definition is same which mean:-"What's today's date?
But,for formal Malay,usually we say "haribulan (hb)" when we want to say the date in complete version which comprises the number of day,the month and the year.
For example:-
Hari ini, 12 haribulan Mac 2015.Which means:-Today is 12th Mac 2015.
However, for formal speaking or writing: "tarikh" means date.
For example:
Tarikh : 12 Mac 2015 (in writing,we usually don't put HB or haribulan after the number,but it considered ok if you want to put HB )
In English version
Date: 12th Mac 2015.