Thermal infrared is heat. All real-world objects emit thermal infrared radiation. This radiation is can be captured with a camera and the results visualized as a "heat picture". These pictures are useful for monitoring the condition of electrical connections or other devices where it is either dangerous or inconvenient to measure in a more conventional way.
Thermal infrared photo of a sugar beet piles. The image shows an area of spoilage in the bottom pile.
The near-infrared is the portion of the electromagnetic spectrum just beyond what the human eye can see. Plants and vegetation are highly reflective in the near-infrared portion of the electromagnetic spectrum. Using special cameras, we are able to identify areas of stress in a crop using this infrared reluctance.
Below is a color and color infrared composite image. This field is at an experiment station, and it contains several different crops. There is a lot more contrast seen in the color-infrared photo than in the normal color image.
Through careful and repeated monitoring of a field, discrepancies can be identified. Things like irrigation anomalies and other sources of stress are visible much sooner in an infrared photo.