BRT VS LRT

According to WIKIPEDIA :

Comparison with light rail / metro systems

Light Rail has reported passenger capacities between 3,500pph (mainly street running) to 19,000pph (fully Grade-separated). "From these findings ... there is little evidence to support the view that LRT can carry more than busways."^[15] By way of example, a light rail system running on two-minute headways with 200-passenger cars operating as single units could carry 6,000 passengers per hour (pph). Theoretically, this same system should carry 12,000 pph with two-car trains, and 24,000 pph with four-car trains just as BRT Systems can/have increased capacity with larger capacity buses and stations.
The Los Angeles Orange Line runs entirely in an exclusive lane and therefore achieves speed and reliability comparable to rail.

Cost 

The capital costs of implementing BRT lines can be lower than up-front costs of constructing LRT lines. A study by the United States Government Accountability Office found that the average capital cost per mile for busways was $13.5 million while light rail average costs were $34.8 million.^[16] However, a huge range of capital costs can be seen, as BRT lines can cost anywhere from $200,000—$55 million per mile, while LRT lines can range from $12.4—$118.8 million per mile.^{[citation needed]} The total investment varies considerably due to factors such as cost of the roadway, station structures, park-and-ride facilities, traffic signal systems and vehicles.

The costs of a running a BRT system is about $13.49 a mile and the total cost for a year of expenditure is $987.80 according to a study done by the GAO. Running a BRT system is much less expensive than running a light rail system. The BRT is also much less expensive than a trolley system.^[17]
Light rail and tram systems require the placement of rails for the entire line. The tram usually avoids the high additional costs for engineering structures, such as tunnels, that need to be built for metro rail systems. Properly maintained rail tends to provide a smoother ride, making it more attractive to riders than road-based systems.
Proponents of light rail point out that the operating costs of BRT are not necessarily lower than light rail. The typically larger light rail vehicles enjoy reduced labor costs per passenger, and the unit capital cost per passenger can be lower than a BRT system.^[18]