Hi ys reddy,
It’s interesting you asked Hitesh ji a non investing related question 
My two cents:
Things are a bit more complicated if you dig deeper. Calcium supplement in form of calcium citrate is much better. Calcium carbonate is harder to digest and hence it is strictly recommended to take it with a meal.
However comparing shelcal and cipcal, both are of calcium carbonate form along with 250IU of Vitamin d3. So rationally speaking, one should go with the cheaper version given the fact that both are produced by good companies.Note that shelcal is from animal source so it would count as non-veg.
I am an aspiring weight lifting athlete so I take 500 mg of calcium citrate with 2000IU of vitamin D3 and 700 mcg of Vitamin K (K1 & K2). Vitamin D3 is necessary for your body to make use of the calcium supplement you are putting in. Vitamin K and vitamin D3 work synergistically. So normally it’s recommended to take vitamin K, D3 and calcium (citrate form recommended but carbonate form is okay with the meal)
Best regards