Final answer:
BLS differs between infants and older children mainly in the compression-to-ventilation ratio, being 30:2 or 15:2 for infants, depending on the number of rescuers, and consistently 30:2 for older children.
Step-by-step explanation:
The sequence of Basic Life Support (BLS) in an infant is different from that of a child aged 1 or older primarily in the compression-to-ventilation ratio.
For infants, the compression-to-ventilation ratio is 30:2 when BLS is provided by one rescuer and 15:2 when provided by two rescuers. In contrast, for children aged 1 and older, the ratio is 30:2 regardless of the number of rescuers.
In addition, chest compressions for infants are performed using two fingers for a single rescuer or two thumbs with the hands encircling the chest for two rescuers, while for older children, a single hand or two hands (for larger children) are used to perform compressions.