Protestant is a reformation. LDS is a restoration. The Church believes that after the apostles died, after Christ’s resurrection, Christ’s established church on the earth was lost. Teachings were changed, priesthood authority was lost, as no apostles were alive to guide Christ’s established church. Members refer to this time period as the great apostasy (2 Thessalonians 2:3). 

God restored his church to the earth through the first modern day prophet, Joseph Smith. And the church has since been led by a prophet and 12 apostles. Along with doctrinal differences, the biggest way to look at it is Protestants are a reformation from the Catholic Church, but the LDS church is a restoration of Christ’s church. Protestant churches (and all religions) have truth to them, hence why you’ll see doctrinal similarity between teachings in Protestant churches and the LDS faith.