There are many differences, but the one I run into the most is concerning the Sacraments. Lutherans believe that God has limited Himself to two means of grace: Word (The Bible Alone) & Sacrament (Holy Baptism & Holy Communion as drawn from Scripture Alone) through which His Holy Spirit works repentance & belief in a person. This is because in His infinite grace He wants us to be certain of our salvation, not always questioning whether we did what was necessary to be saved.
Southern Baptists do not believe in the true presence of Christ's body & blood in Holy Communion which is umbilical & therefore contrary to the Ecumenical Creeds (Apostles' Creed, Nicene Creed, Athanasian Creed) that have been derived from Scripture in response to popular heresy.
I'm just learning myself as a lifelong LCMS Lutheran that a denial of the real presence is essentially a denial of Christ's true testimony (i.e. "this IS my body...given for you.... This cup IS the new testament, in My blood, which is shed for you for the forgiveness of sins." (Matt.26:26, 28; 1 Cor. 11:23-24) & His true nature (i.e. true God & true man at the same time). By denying the real presence, Baptists among others try to separate the divine & human natures of Christ which should not & cannot be divided else He be stripped of one or the other.
Another big difference is this: Lutherans believe: It's "By God's GRACE ALONE, through FAITH in Jesus Christ ALONE, as written in SCRIPTURE ALONE" that a person is saved. In short, it is for this reason that we believe that an infant can & should be baptized. We believe that regardless of the mode (Emerson or sprinkling) the Holy Spirit is capable & will work saving faith in the life of an infant through Baptism (the combining of God's Word with the water is what gives Baptism it's power, not the water itself or the actions themselves, nor the holiness of the person or pastor administering it).
Southern Baptists may also declare "by grace through faith", but the means by which this happens are wish-washy & depend on the sincerity of the person's prayer or confession that Christ is Lord, etc. rather than on Christ's saving work alone. In other words, they subtly but certainly return to the error of the Roman Catholic doctrine of works righteousness. This is why they do not believe in infant baptism--because faith is dependent on the person, not the Holy Spirit granting faith. They also insist on full Emerson, which provides a good illustration of being buried with Christ, but nevertheless is not necessary.
See Ephesians 2:8-9.