It's mostly marketing jargon. SSD manufacturers are trying to differentiate themselves from the competition.
SSDs have no moving parts so they are as reliable (if not more so) as HDDs.
Hard drives have been around since the late 1950s, and consumer hard drives have been around since the 1st personal computers were available in the 1970s, so the technology is pretty mature and reliable.
The 1st consumer SSDs (the Intel X-25E) were available in October 2008.
Since the tech is relatively new SSD manufacturers use terms like "Enterprise-grade" to reassure people who might be nervous about switching from HDD to SSD.