Final answer:
The T-weld and lap weld are known as "fillet" welds, which are used to join metal pieces at right or oblique angles, unlike butt welds that join along a plane.
Step-by-step explanation:
The two types of welds known as "fillet" welds are the T-weld and lap weld. A fillet weld is a type of weld that joins two pieces of metal together at a right angle or an oblique angle by filling the seam with weld material. The T-weld is named so because it joins two metal parts at a right angle, resembling the letter 'T'. The lap weld is used to join two overlapping pieces of metal. These welds are different from butt welds, which join two pieces along a single plane.