PHYSICS-----LENS FORMULA

IS LENS FORMULA SAME WITH LENSMAKER'S FORMULA?
No. They are different. The lens formula is commonly called the "thin lens formula". It relates the focal length of a spherical lens with the object and image distances.
The lens maker's formula, on the other hand, relates the focal length of the lens with the lens material, surface curvature of the spherical lens. As the name implies, by knowing the lens material (which is indicated by the refractive index of that material), lens of the desired focal length can be made by adjusting the surface curvature of the lens material.

IN LENS MAKER'S FORMULA, WHAT IS (N-1) REPRESENT?
The symbol N represents the refractive index of the lens material. The "1" is, in fact, the refractive index of air. Refraction of light through a spherical lens depends on the difference in refractive indices of the lens material and the medium where the lens is placed. The larger the difference, the more is the refraction, and hence a shorter focal length is resulted. When the lens is placed in air, the difference in refractive indice is thus (N-1). The larger the value of this factor (N-1), the shorter is the focal length. Therefore, it is apparent that the focal length of a spherical lens is inversely proportional to the factor (N-1).
can you guys talk something more about these two formula??
The two formulae serve different purposes, as explained in the first question. The lens makers formula is used to calculate the focal length of a spherical lens after the refractive index of the lens material and its surface curvature are known.
After knowing the focal length of the lens, the image formed by this lens at different object distances can be found by using the "thin lens formula",

The lens-makers formula is actually a more general form of the lens
formula. It can be applied to meniscus lens. In the formula, (N-1) only
represent the differences between the refrctive index and one, which
I THINK with no special meanings.
The lens formula, is a simplied formula and cannot be applied to
meniscus lens. It is generally used to calculate the biconcave (or
biconvex) lens.
As for the meniscus lens, it is a lens with two curved surfaces.
The picture of different lens can be read on:
http://en.wikipedia.org/wiki/Lens_(optics)#Lensmaker.27s_equation