Synth strings sound like the original "string synthesizers" like the Solina String Ensemble (famously present in Jarre's Oxygene, albeit played on somewhat different instrument, and through a phaser). They tend to be scratchy, nasally, thin, etc.

Sampled strings cen be really convincing. Listen e.g. to https://vi-control.net/community/threads/phaeton-symphony-by...