Ota images for nexus 5
Google has noted here:


  [Manually updating your Nexus device using OTA binary image files] has the same effect of flashing the corresponding factory images, but without the need of wiping the device.


(Emphasis mine)

On the contrary, by OTA update, if you meant incremental platform/system updates, then even so, user data would not be wiped out.

User data would also not be wiped out if the factory image files are flashed manually (not via the included script) and userdata partition is skipped from flashing.

Note: It is my assumption that the question refers to data as everything created or added by the user (directly or indirectly - via an app or system) since the last time the factory reset was done. Data hence corresponds to files stored in the userdata partition, mounted at /data. 
 In simpler terms, data here is everything that would be deleted if a factory reset is performed on the device.