The acidophilus I got from the USA has the following good bacteria:

Lactobacillus acidophilus
Lactobacillus bulgarius
Lactobacillus thermophilus

It also has folic acid and dry milk (lactose free) in it.

The acidophilus from the UK has the following good bacteria:

Lactobacillus acidophilus
Bifidobacterium bifidum

So, both of the products have Lactobacillus acidophilus in common, which is the most important good bacteria.

Probiotics do the following things:
• They manufacture some of the B Vitamins including niacin (B3), pyridoxine (B6), folic acid, and biotin.
• They actively produce antibacterial substances which kill or deactivate hostile disease-causing bacteria. They do this by changing the local levels of acidity, by depriving pathogenic (disease-causing) bacteria of their nutrients, or by actually producing their own Antibiotic substances which can kill invading bacteria, viruses, and yeasts. Naturally enough they are doing this to preserve "their" territory.
• Some bacteria (such as bifidobacteria and acidophilus) have been shown to have powerful anticarcinogenic features which are active against certain tumors. They also kill most food poisoning bacteria.

Lactobacillus Acidophilus
This is the main inhabitant of the small intestine in humans and animals. It is also found in the mouth and vagina. Acidophilus manufactures lactase to digest milk Sugar and produces lactic acid which suppresses undesirable bacteria and yeasts. Some strains produce natural Antibiotics . They also lower cholesterol levels and kill candida yeasts, and are very susceptible to poor diet and stress conditions, pollution, and Antibiotics such as penicillin.

Lactobacillus Bulgaricus
This is a transient but very important bacteria. Together with Streptococcus thermophilus it makes yogurt. Some strains of bulgaricus and thermophilus also produce Antibiotics which kill harmful bacteria. By manufacturing lactic acid these bacteria encourage a good environment for the resident bacteria such as acidophilus and the bifidobacteria.

Bifidobacterium Bifidum
The bacteria produce a number of specialized acids and use these to prevent colonization of the large intestine by invading bacteria, yeasts and some viruses.

Certain drugs, especially antibiotics, can severely upset this delicate balance (penicillin will kill friendly bacteria just as efficiently as it will kill disease-causing bacteria). Steroids LIKE THE CREAMS PRESCRIBED BY DOCTORS (hormonal drugs such as cortisone, ACTH, prednisone, and birth control pills) also cause great damage to the friendly bacteria flora.