Psalm 18.49
Septuagint

dia touto exomologhsomai soi en eqenesi, kurie, 
kai tw onomati sou yalw

New Testament - Romans 15.9

dia touto exomologhsomai soi en eqenesi 
kai tw onomati sou yalw

Septuagint

Therefore will I confess to thee, O Lord, among the Gentiles, and sing to thy name

New Testament

Therefore will I give praise unto thee among the Gentiles, and sing unto thy name

Masoretic Text

Therefore I will give thanks unto thee, O Jehovah, among the nations, And will sing praises unto thy name

Comments:  The NT and the LXX.  Brenton and the ASV translators have chosen two different but acceptable English expressions for the Greek word exomologhsomai.  The RSV has “extol” where the ASV provides “give thanks.”  The NIV agrees with the RSV, translating with “praise.”

The other difference involves what is sung.  The NIV and the RSV translate with “sing praises.”  The Greek word yalw means to pluck strings or to sing accompanied by a harp, and does not necessarily imply praise.  However, this seems too minor a difference to note in the tables.