From your photo, you have mild to moderately severe inflammatory acne rather than severe cystic acne.
Differin gel will certainly be effective in your treatment. Especially when combined with topical benzoyl peroxide. Doctors may also choose to give you a short course of oral antibiotics such as doxycycline to control the inflammation more rapidly.
After successful control of your acne inflammation, it will be useful for you to continue the application of Differin gel nightly as maintenance therapy. This is to prevent relapses of your acne issue.
Other than Differin, doctors may recommend topical tretinoin as it is also effective for acne treatment and maintenance.