A tagline is for the life of a brand, it usually sums up a thing such as a brand.
Taglines are used online and offline, often associated in close proximity to the logo.
Taglines are memorable. Technically creative!
A slogan is more of an advertising campaign spearhead, more product/service specific.
I would say hands down Taglines would win Slogans if it came to a one on one. However it’s a family unit. Slogans are the children of taglines.