In a nut shell Flomax works different than Finasteride and sometimes both
are used together for prostate BPH.

Flomax is used to treat the symptoms of a prostate gland condition called
BPH (benign prostatic hyperplasia, also known as enlarged prostate).
Tamsulosin is an alpha-blocker that works by relaxing the muscles in the
bladder neck and prostate. Relaxing these muscles leads to relief of
symptoms of BPH such as the feeling of needing to urinate frequently or
urgently, weak stream, difficulty in beginning the flow of urine, and the
need to urinate during the middle of the night.

Finasteride is used to shrink an enlarged prostate (benign prostatic
hyperplasia or BPH) in adult men. It may be used alone or taken in
combination with other medications to reduce symptoms of BPH and may also
reduce the need for surgery.

Finasteride may improve symptoms of BPH and provide benefits such as
decreased urge to urinate, better urine flow with less straining, less of a
feeling that the bladder is not completely emptied, and decreased nighttime
urination.

This medication works by decreasing the amount of a natural body hormone
(DHT) that causes growth of the prostate.

Decreased sexual ability/desire may occur. In some men, this medication can
decrease the amount of semen released during sex. This is harmless.
Finasteride may also increase hair growth. If any of these effects persist
or worsen, notify your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because the benefit
to you is greater than the risk of side effects. Many people using this
medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side
effects occur: lump in the breast, nipple discharge, breast
enlargement/tenderness/pain, pain in the testicles, inability to urinate.

A very serious allergic reaction to this drug is unlikely, but seek
immediate medical attention if it occurs. Symptoms of a serious allergic
reaction may include: rash, itching, swelling, severe dizziness, trouble
breathing.

If you notice other effects not listed above, contact your doctor or
pharmacist.

Also it is used as a medication for hair growth.