Hello and welcome to JustAnswer,
Great question. The answer is that the 'tartrate' is a more immediate release medicine. Depending on your particular blood pressure problem it might require additional doses per day.
Metoprolol succinate is more sustained or extended release and is therefore truly a once a day medicine.
This is probably fine and you might simply ask your physician if he or she wishes to do a 3 day blood pressure check with you on the shorter acting form of the drug.
If you have mild hypertension then this probably is going to make no difference at all to you in the long run.
I am standing by if you have questions for me.
i have run a check on your medicines in terms of interactions and the only caution holds for whichever form of metoprolol you are taking and it is that hydrochlorothiazide and metoprolol can affect your serum potassium levels.
if postassium problems have not presented for you in the past this change will not affect you.
other than that there are no significant interactions and you may rest easy.