It depends on the installation. Generally, it is cheaper to install a shower, but this also depends on the fixtures you choose and the size of the shower. For a more detailed answer, it is best to consult with a local contractor.

It can be cheaper to install a tub, but it really depends on your specific situation. For example, if you have to move plumbing around in order to fit a tub in, that can add extra costs. Or if your water heater isn't big enough to handle both showers and baths, you may need to upgrade that too. So it's really hard to say without knowing more about your home and your specific needs. One thing is for sure, though: a lot of people prefer showers because they're faster and more efficient. So if you're trying to make the most cost-effective decision, a shower may be the way to go.