May I suggest that the issue is less about antenna sensitivity than about the time required to acquire satellites under different contexts.
Although the original poster claimed that both systems were deployed in the same field, it matters whether one of the systems had more recently acquired a lock - in the last minutes or 2 h. If such, the system is said to 'hot start'. If you turn on a GPS receiver from a 'cold start' (haven't used the system for many hours or days) ~45 s is not unusual*. All this is related to the currency of that devices GPS ephemeris data.
This has to do with the updating of satellite position and timing information which is done every few hours and not with hardware.
Global Positioning System (GPS) navigation satellites transmit electronic ephemeris data consisting of health and exact location data that GPS receivers then use (together with the signal's elapsed travel time to the receiver) to calculate their own location on Earth using trilateration.
Again, nothing to do with different satellite constellations (e.g. GLASSNOS) as the basic process of satellite acquisition is common across that factor. The GPS chips are made by companies like Broadcom / Philips / Sony. DJI won't have resources to design these.
*Look at https://www.sparkfun.com/products/465
for data on tine ti GPS lock.