They are really the same thing, just occurring in different places on the foot. It's really a matter of nomenclature. We usually call those areas of thickened skin that occur on the top of toes, a "corn", and we call the same condition when it occurs elsewhere on the feet, a "callus". (The proper spelling, by the way is "callus", not "callous". "Callous" is an adjective, so this would be the proper spelling if used to modify a noun, as in describing "a callous person".)
Now, to make things confusing, sometimes small calluses on the bottom of the foot that occur with cores are called "seed corns". And a severe form of callus on the bottom of the foot is often called an IPK (Intractable Plantar Keratosis).
Regardless of terminology, though, any of these conditions can be painful. Most podiatrists will tell you that the most severe and most painful types of these lesions are the ones with a hard core, most commonly seen in smokers--(which is still another reason to quit).
What can you do to treat them?
The first thing you can do for corns is wear good, supportive shoes with a wide toe box, laces and a low heel.
You can also treat them at home by using a pumice stone or "medicated" corn pads. The "medication" is really just an acid, used in the attempt to dissolve the dead skin, so you have to be careful using them. They can cause uncomfortable burns to healthy skin if improperly used. These treatments should never be used by diabetics or those with poor circulation, as they could lead to devastating problems such as gangrene, infection and amputation. A safer method of removing corns is to see your podiatrist, who can remove the lesions more quickly, less painfully and more safely than you can do it at home.
The problem with simply removing the lesion, though, is that the underlying cause of the problem is not addressed, and the lesions tend to come back. To try to prevent their return, you could try various types of over-the-counter padding or custom-made orthotics or appliances to redistribute and cushion the lesions.
If the pain is unresponsive to conservative care, and if x-rays show an underlying bony problem, surgical correction may be indicated. There are several types of procedures that may be chosen, but as a rule, these procedures can be done under local anesthetic, and often (but not always) patients are allowed to bear weight immediately afterward. Each potential procedure is unique, however, and if this method is considered, you need to have a thorough consultation for specific information unique to your foot.
In theory, it is best to keep a blister intact, because if the blister is opened, it could become a source for infection.
In practice, however, blisters can be quite uncomfortable. In these cases, it is probably best to pop the blister with a sterile instrument, and drain out the fluid. Ideally, it would be best to have a podiatrist do this for you, as we have clean, sterile instruments designed to do just this sort of thing. But if you are in a position where you cannot get to a podiatrist, you may wish to try to pop it yourself, in which case you should sterilize your equipment by boiling it for fifteen minutes beforehand.
The roof of the blister should be kept intact, as this will act as a barrier to infection, and protect the tender layer of skin below.
An antibiotic cream or ointment may then be applied, and you can protect the blister with a sterile dressing.
How can blisters be prevented?
Precautionary measures that can be taken to prevent blisters from forming include: careful fitting of shoe gear to relieve pressure over bony prominence and to prevent sliding of the foot; application of mole skin padding over areas of irritation; wearing well fitting absorbent sport specific socks or two pairs of socks with a thinner pair next to the skin; and the application of foot powder between the toes to dry the skin.
What is a Bursa?
A bursa is a fluid-filled sack that separates and cushions certain tissues, so the separated structures don't rub together and get irritated. For example, you have a bursa between the back of your heel bone and the Achilles Tendon. Without that bursa, the Achilles Tendon may become irritated and inflamed by the heel bone.
Sometimes in the process of protecting a structure from becoming inflamed, the bursal sac, itself, may become inflamed. This is called Bursitis.
How can you tell whether it's the bursa or another tissue that's inflamed?
It's not easy sometimes. There may be a number of soft tissues in the area of a bursa which may become painful, swollen, red and inflamed. In order to make certain someone has bursitis, it's best to be assessed by an expert.
What can you do to treat bursitis?
There are a wide variety of treatments for bursitis. Rest, ice, compression, elevation, accommodative padding, orthopaedic appliances, anti-inflammatory medications, steroid injections, immobilization, changes in shoe gear, and surgery are just some of the examples of possible treatments that may be used to treat bursitis.