Вот Вас описание с garmin.com:
DC50:
Unit dimensions, WxHxD: 3.5" x 1.9" x 1.8" (9.0 x 4.9 x 4.6 cm)
Collar length: 12" (30.5 cm) to 20" (50.8 cm) adjustable collar
Weight: 7.5 oz (212.0 g) for transmitter and antenna; 10.2 oz (289.0 g) total weight
Battery: Li-ion rechargeable
Battery life: 26–54 hours (user adjustable transmit rate of 5, 10, 30 or 120 seconds)
Waterproof: 10 m (33 ft)
High-sensitivity receiver: yes
T5:
Unit dimensions (WxHxD): 3.5" x 1.75” x 1.85" (7.8 x 4.4 x 4.4 cm)
Weight: 6.6 oz (188.0 g) for transmitter and antenna; 9.3 oz (265.0 g) total weight
Battery life: 20-40 hours
Battery type: rechargeable lithium-ion pack; user replaceable
Interface: USB
Water rating: 1 ATM (10 meters)
High-sensitivity GPS/GLONASS receiver: Yes
GPS antenna: top, orange
Stimulation/Vibration/Tone: No
LED beacon lights: Yes
Frequency band: MURS (The T 5 and TT™ 15 are only compatible with the Astro® 320 and the Alpha™ 100. The T 5 and TT 15 can be configured for operation with either handheld but cannot be tracked simultaneously by both the Astro 320 and the Alpha 100)
Rescue mode: Yes
Replaceable collar straps: Yes
Collar compatibility: 1” (2.54 cm)
То есть по весу Т5 немножко легче.
Что касается размера, почти одинаковые. Забавно, что гармин считать не умеет
