The hotend and heat bed thermistor are both 100K NTC resistor with beta 3950.
The stock hotend thermistor uses a glass bead thermistor.
The stock heat bed uses a SMD thermistor but can be easily replaced with a glass bead type.

A few stock replacement options listed below.

As of motion controller firmware version 26 the MP Select Mini is no longer limited to only using a 3950 thermistor for the hotend.
Version 27 added this ability to the heat bed.

Using the custom G-code command M561 the thermistor type can be changed for the hotend and heat bed.
The hotend and heat bed can each use a different type of thermistors.

See the Extended G-code Table page for instructions on how to use custom G-code command M561 - Change thermistor type (Hotend and/or Heat bed)

EPCOS 100K Thermistors B57540G0104F000, B57560G104F, and B57560G1104F have similar Beta values compared to the stocks Beta value of 3950. Because of this you can use any of them as replacement thermistors. Use the stock thermistor setting of Type P0.

Characteristics of 104GT-2 and 104NT-4-R025H42G are nearly identical. Type P1 is used for either thermistor.

GiGDigit - Thermistor - MP Select Mini V1/V2

Amazon.com - RioRand(TM) Upgraded 10 pcs 100Kohm NTC Thermistors
Leads are not insulated. You must insulate the leads before using

Amazon.com - Anycubic NTC 3950 100K Thermistor with 1 Meter Wiring and Female Pin Head for RepRap 3D Printer Heatbed or Hot End Pack of 5PCS
NOTE: The JST connector can be cut off. You may also choose to cut the wire closer to the thermistor to use the existing wiring.

Amazon.com - [3D CAM] 3 PCS NTC3950 Thermistors for RepRap 3D Printer Extruder or Heated Bed pre-wired with Teflon Insulated Wiring
NOTE: Wired - No female pin connector

Amazon.com - Mmei 5pcs NTC 3950 100K Thermistor with 1 Meter Wiring and Female Pin Head for RepRap 3D Printer Extruder Heated Bed pre-wired or Hot End
NOTE: Wired - With female 2 pin connector (connector may not be the correct size but can be cut off)

Amazon.com - Happisland 5pcs NTC 3950 100K Thermistor with 1 Meter Wiring and Female Pin Head for RepRap 3D Printer
NOTE: Wired - With female 2 pin connector (connector may not be the correct size but can be cut off)

Amazon.com - 2pcs M3 Screw on Modular Design NTC 3950 100k Thermistor with 1m Cable Wire
NOTE: The M3 stud screws into the heater block.