This shouldn't be too tough. Tintoretto's Last Supper is more dynamic and dramatic but Christ is in the center as in Leonardo's Last Supper. The spiritual is blatant in Tintoretto's painting too, but in Leonardo's version, not even Christ has a halo. You can also talk alot about the differences in how the two artists make balance in the painting and how they create depth. In Leonardo's work, one of the things he does to create balance is grouping the apostles into groups of three. You can compare and contrast their styles, their techniques, and their goals in making the piece.
Tintoretto is dark-lightened only by fire, and the time of day is not as obvious. The painting's surrounding is almost in a bar-like place, and the picture is not as intimate as da Vinci's.
With the exception of color, which is better preserved in the Academy Calvary, all the outstanding qualities of Tintoretto appear in this strikingly original and complex design. It is characteristic in using intensified streaks of light along limbs and garment-folds, to emphasize the direction of movement, and thus heighten the effect of dramatic action. These twisting, darting gleams of light, flaring out suddenly from deep shadow in the hanging lamp and in the haloes of Christ and the disciples, give the scene an eerie radiance and an air of quivering energy. At the same time they serve to distinguish and organize the picture's many details, silhouetting dark heads against the light, or trans-fixing here and there some white gesturing hand or shoulder against the darkness. Such accents bring out the dramatic and emotional import of each principal element, and its part in the flowing rhythm of movement, while minor details sink into the shadows.
Largely through gradations in light, a distinction is made between the hovering angels and the human bodies below — the former translucent, weightless, insubstantial, vaporous forms lit by the flare; the latter lithe but solid, straining muscular limbs....