One of the big differences between the 109 and the 38 is torque. The 109 has lots of torque. The 38 has no torque. As the 38 driver you can take advantage of that difference. Torque is most prevalent at low speeds, high angles of attack, and high power settings. So if you are both in a maneuver that fits that description, such as a Flat Scissors, you know he will have a very hard time rolling right, if he can at all. Meanwhile you are still free to roll to the right to your heart's desire.
So keep an eye open for a chance to bring the fight slow and then give him two options; turn right or dive away. If he tries to turn right, you can probably gain some massive angular advantages or maybe a game ending shot. If he recognizes the danger and dives away, you will have the high ground and can work him down with BnZ attacks.
Of course there are differences depending on what models you're talking about. 38G vs 109F4 is going to be a lot different than 38L vs 109K4.