The difference between pipes and tubes is simply in the way it is sized. PVC pipe for plumbing applications and galvanized steel pipe for instance, are measured in IPS (iron pipe size). Copper tube, CPVC, PeX and other tubing is measured nominally, which is basically an average diameter. These sizing schemes allow for universal adaptation of transitional fittings. For instance, 1/2" PeX tubing is the same size as 1/2" copper tubing. 1/2" PVC on the other hand is not the same size as 1/2" tubing, and therefore requires either a threaded male or female adapter to connect them. When used in agricultural irrigation, the singular form "pipe" is often used as a plural.
General employment within the construction sector is sensitive to changes in the economy. But job growth for plumbers is projected to be faster than the average for all jobs. New buildings and residences are being built to comply with stricter water efficiency standards and companies housed in older structures are hoping to retrofit to use more energy-efficient systems, so opportunities are in abundance. According to the Bureau of Labor Statistics, there should be a hiring spurt of 16 percent for plumbers by the year 2026, which translates to about 75,800 new jobs.