Transparent: Having the property of transmitting rays of light, for persons/objects on the opposite side, to be “distinctly seen”: Rose colored glass is transparent.
Translucent: Permitting light to pass through with enough dispersion, for persons/objects on the opposite side, to not be clearly visible: Frosted window glass is translucent.
Optically Opaque: Backlit print can glow, but is extremely difficult, if not impossible, to see items or movement through the image.
TechClear: technically clear like the plastic liner which protects smart phones. The slight mirage or watery film can be seen through but does not have the same optical clarity of glass. Most of the print industry prints on films like this.
Optically Clear: Clear glass which blocks very little visibility. The only issue is the reflective quality of the glass surface, not the actual glass itself. HDClear is typically printed on 4-mil optically clear film. It looks like glass when the project is complete