Are SI system and Metric systems the same thing?
No. The SI system is a metric system, but the metric system isn't SI.
Please note that the metric system is the world-wide standard. If by "standard" you mean the Imperial system (the system commonly used in the USA), the similarities are that the systems are designed to measure, and that they both have units to measure the same type of thing, for example length/distance, area, volume, temperature, etc.
Metric system was created for the purpose to be easy to use and base on 10. The English system was the traditional system when people had nothing but their hands and feet so that used that to measured things. This is why metric is global (except 3 countries) now because it's easy. It's also best if everybody uses the same measuring systems since we have a world economy now. It's easier to sell things to…
No. While SI is certainly 'metric', the 'metric system' is not necessarily SI. For example, an earlier metric 'standard' was known as the 'cgsA' system, whose base units were the centimetre, the gram, the second, and the ampere. Later, this was changed to the 'mksA' system, based on the metre, the kilogram, the second, and the ampere. SI is a development of the mksA system.
The basic things we measure are Length, Mass, and Time. In the Metric system also known as the CGS system, they are Centimeter, Gram, and Second. In the Imperial or British system also known as the FPS system, they are Foot, Pound, and Second. The Second, the unit of time is the same in both systems.
This is one question where no clear "yes" or "no" can be given. Metric system is a general term for several systems of units. SI is one of them, based (among other units) on meter, kilogram, second. It is in the subcategory of MKS (thus called for those three base units). Older systems (also labelled "metric systems) were often CGS, in other words, the base units included centimeter, gram, and second.
A tonne is a metric unit of 1000kg and is the metric equivalent of a ton., ie a metric ton. A metric tonne is a tautological description of a tonne, ie the "metric" part is unnecessary as "tonne" is the [spelling of] "ton" in the metric system of units. (A "metric tonne" says a "metric metric ton" - just like a "pin number" is a "personal-identification-number number".) Or to put it another way, they are…
They are the same thing. One tonne is 1 metric tonne. A tonne and a metric tonne are the same thing. A tonne is a unit of mass. 1 tonne = 1000 Kg. The tonne or metric ton is a non-SI metric unit of mass equal to 1000 kilograms; it is thus equivalent to one megagram. So,tonne and metric ton is the another name.
Metric (SI for International System in French) was developed to replace archaic measures such as those of the "english system" or those used in France before the revolution. For example, Canada once used the Imperial gallon for gasoline; a gallon, but larger than the US gallon. There are no common units between these systems of measurement, and converting from one to another leads to all kinds of problems. A metric unit is the same everywhere…