I just preached on Romans 7:14-25, and it really struck me this past week how different the struggle in this chapter is from the one described in Galatians 5:16-18.
The former is a struggle between who the subject is and who he desires to be. The latter, on the other hand, is a struggle between who the subject is and who he was but is no longer.
In Romans 7, the "wretched man" says the following about himself: he is carnal (v. 14); he is sold as a slave to sin (v. 14); he has been taken captive by indwelling wickedness (v. 23); and he is powerless against temptation (v. 18). In a word, when the war is waged between his will-power to obey the law and his native corruption, the best defense he can muster is the ability to serve God in his head while sinning with his body (v. 25).
The subject of Galatians 5, however, has been "for freedom set free" by Christ (v. 1), is "called to freedom" (v. 13), is "led by the Spirit" and is consequently "not under the law," for he "belongs to Christ Jesus" (v. 24), has "crucified the flesh" (v. 24), "lives by the Spirit" (v. 26), and is therefore called to "walk by the Spirit" (v. 26).
Furthermore, the struggle in Romans 7 is a battle between ego and nomos ("I" and "law"), while the conflict in Galatians 5 is between sarx and pneuma ("flesh" and "Spirit").
And finally, in Romans 6:14 Paul draws the direct connection between being under the Mosaic law and being under sin's dominion. Now if the subject of Romans 7 explicitly claims to be under sin's dominion, we have no choice but to conclude that he is therefore under the Mosaic law. The Galatians, however, are explicitly told that they are not under the law, but rather, they are led by the Spirit.
So yes, two very real struggles are depicted in these texts. But one is from the perspective of a carnal slave who wishes he could be spiritual but can't, while the other is from the standpoint of a Spirit-led son who keeps forgetting who he is, and falling back into what he used to be.