The prostate is normally a walnut sized gland that surrounds the neck of the bladder in males. Its role is to release prostatic fluids which helps make up part of the semen. When the prostate increases in size for a number of reasons, it can compress the urethra (tube that connects the bladder to the outside via the penis) which can cause urinary problems and pain. 

• increased frequency of urination
• urgency
• difficulties with initiating or weaker urine stream
•  incomplete emptying of the bladder, which can lead to urinary retention and UTIs
• dribbling at the end of urination and straining to empty. 

Symptoms of pain can include

• painful urination
•  painful ejaculation
• groin/abdominal pain

In any case, you can have an enlarged prostate and have no symptoms. 

Both benign prostate hyperplasia and prostatitis can enlarge the size of the prostate. 

Prostatitis is caused by infections (usually bacterial), traumatic injury or other related health problems and refers to inflammation of the prostate. 

You can have chronic or acute prostatitis. 

Benign prostate hyperplasia usually occurs in men over 50 years old where there is a non-cancerous enlargement of the prostate