What is the difference between Peyronie's disease/disorder and phimosis?

I've read that both can create a "bottleneck" effect of the penis. How can one tell if this effect is from Peyronies or phimosis? Is there a way to differentiate the two?

I know seeing an urologist is the best. Any additional information other than that would be greatly appreciated.

look it up on uptodate. Your primary care doctor could help you as well.

I believe Peyronie's disease is caused by scarring which develops as a subcutaneous disease in the tissue of the penis which may make it curve (when it happens in the finger its called "trigger finger", a much better known entity) and you can surgically "release" the contracture by cutting through it. Thre is usually a linear sort of "cord" like feeling running from the base to the tip of the penis. Phimosis, I believe, happens in uncircumcised men when the foreskin is pulled back behind the head of the penis and basically gets stuck there.

The answer above is pretty close. Peyronies disease is a disfiguration of the penis resulting in an extreme curvature of the penis shaft. This is often a very painful condition and needs to be treated promptly, most often surgically. It can be a quick or slow onset depending on the root cause and will have different "feels" depending on the condition.
Phimosis is a hardening or keratinization in most cases of the prepuce or foreskin in uncircumsized men. While it can happen to those men who were circumsized and retain a good amount of skin, it is most often found in uncut men. This is easily remedied by stretching of the foreskin. If the condition is bad enough, it may need a doctor's help. In america it is not uncommon for many people to automatically suggest a circumsicion. This is not neccessary!!! If you have all your parts, keep them. There is no medical reason for circumcision except in extreme cases! Even if you have an extreme case, most time it can be fixed by a simple dorsal slit instead of actual circumcision.
Bottlenecking can be a result of phimosis, as the head is trapped in front of the foreskin when it is pulled back due to the constrictiveness of the skin. But most often the case, a bottleneck penis is the result of simple genetics in the way that your penis is shaped. Again this can be helped over time as in stretching the foreskin, you can "jelq" or manually enlarge the head of your penis to counteract the physical appearance. This takes time though, although it is possible.