They both have the same meaning but for me, using "IKA" sounds more formal than "PANG" and sometimes depends on some Tagalog dialects. Also, "PANG" is more common than "IKA".

I think what you are trying to say that these are ordinal numbers (e.g. first, second, third). There is a quick and dirty way to learn it, dates = ika and ranking = pang. IKA = for dates and more FORMAL (e.g. February 3rd = Ika-tatlo (ikatlo) ng Pebrero) PANG = for ranking and INFORMAL way (e.g 3rd from the left = pangtatlo (pangatlo) mula sa kaliwa) Just remember (DIRP or Date, Ika, Ranking, Pang), hope this helps and makes you remember it.